The other template files do not add `frozen_string_literal`, so should
behave the same.

Ref: #30342, #30348.

https://buildkite.com/rails/rails/builds/61362#99165d42-172d-4ad5-bf72-b29d8cd44f3e/995-1006

Use WeakRef in Reaper to avoid leaking connection pools

Use a single thread for all ConnectionPool Reapers

https://buildkite.com/rails/rails/builds/61358#a78ee50e-30b5-48a2-858f-63eba287d919/1290-1298

This reverts commit a1ee4a9f.

Even if a1ee4a9f is applied, CI is still flakiness.

https://buildkite.com/rails/rails/builds/61252#2c090afa-aa84-4a2b-8b81-9f09219222c6/994-1005
https://buildkite.com/rails/rails/builds/61252#2e55bf83-1bde-44a2-a4f1-b5c3f6820fb4/929-938

Failing tests by whether schema cache is filled or not, it actually
means that whether SCHEMA SQLs are executed or not is not target for the
tests.

So I've reverted commit a1ee4a9f which filling schema cache before
`assert_no_queries`, and replace `assert_no_queries` to
`assert_queries(0)`.

Fix unexpected select_tag delete behavior when include_blank is present

Don't round off subseconds unless necessary

Allow symbol (i.e. quoted identifier) as safe SQL string

[documentation][ci skip] stringify_keys and symbolize_keys have stable results.

The initializer receives `nil` for these options when no cofigurations were given:
https://github.com/rails/rails/blob/v6.0.0.rc1/activerecord/lib/active_record/railtie.rb#L91-L97

Change comments

[ci skip]

Wrap ActionView cache expiry in a mutex

 Bump Gemfile entry jbuilder version

Remove compatibility module from docs [ci skip]

[CI skip] Put :nodoc: on method that raises NoMethodError

Testing the result of `capture_sql` is fragile, it is due to whether
SCHEMA SQLs are executed or not depends on whether schema cache is
filled or not.

https://buildkite.com/rails/rails/builds/61248#a5b9dc59-ff0c-40c0-b56e-0895662fbc4c/993-1004
https://buildkite.com/rails/rails/builds/61248#1157b389-f2c7-4554-b6e5-a37624a0e74a/996-1005

I've confirmed all `capture_sql` use cases in our code base, all cases
won't expect SCHEMA SQLs are included.

```
% git grep -n capture_sql
test/cases/associations/belongs_to_associations_test.rb:202:    sql = capture_sql { comment.post }
test/cases/associations/belongs_to_associations_test.rb:204:    assert_not_equal sql, capture_sql { comment.post }
test/cases/associations/has_many_associations_test.rb:169:    sql = capture_sql { post.comments.to_a }
test/cases/associations/has_many_associations_test.rb:171:    assert_not_equal sql, capture_sql { post.comments.to_a }
test/cases/associations/has_many_associations_test.rb:276:    expected_sql = capture_sql { author.thinking_posts.delete_all }
test/cases/associations/has_many_associations_test.rb:281:    loaded_sql = capture_sql { author.thinking_posts.delete_all }
test/cases/associations/has_many_associations_test.rb:289:    expected_sql = capture_sql { author.posts.delete_all }
test/cases/associations/has_many_associations_test.rb:294:    loaded_sql = capture_sql { author.posts.delete_all }
test/cases/associations/left_outer_join_association_test.rb:22:      queries = capture_sql do
test/cases/associations/left_outer_join_association_test.rb:49:    queries = capture_sql { Author.left_outer_joins(:posts).to_a }
test/cases/associations/left_outer_join_association_test.rb:54:    queries = capture_sql { Author.joins(:posts).left_outer_joins(:posts).to_a }
test/cases/associations/left_outer_join_association_test.rb:60:    queries = capture_sql { Author.left_outer_joins({}).to_a }
test/cases/associations/left_outer_join_association_test.rb:65:    queries = capture_sql { Author.left_outer_joins([]).to_a }
test/cases/associations/left_outer_join_association_test.rb:78:    queries = capture_sql { Author.left_outer_joins(:essays).to_a }
test/cases/associations_test.rb:384:    log = capture_sql do
test/cases/associations_test.rb:399:    log = capture_sql do
test/cases/associations_test.rb:414:    log = capture_sql do
test/cases/associations_test.rb:429:    log = capture_sql do
test/cases/associations_test.rb:444:    log = capture_sql do
test/cases/associations_test.rb:459:    log = capture_sql do
test/cases/reflection_test.rb:307:    expected_sql = capture_sql { hotel.recipes.to_a }
test/cases/reflection_test.rb:312:    loaded_sql = capture_sql { hotel.recipes.to_a }
test/cases/relation_test.rb:212:      queries = capture_sql { Author.joins(:posts).merge(Post.joins(:comments)).to_a }
test/cases/relation_test.rb:232:      queries = capture_sql { Post.joins(:author, :categorizations).merge(Author.select(:id)).merge(categorizations_with_authors).to_a }
test/cases/relation_test.rb:347:      log = capture_sql do
test/cases/scoping/relation_scoping_test.rb:146:      log = capture_sql do
test/cases/scoping/relation_scoping_test.rb:159:    log = capture_sql do
test/cases/test_case.rb:33:    def capture_sql
test/cases/test_case.rb:41:      capture_sql { yield }
```

Fall back to type casting from the connection adapter

Return parameters enumerator from transform_keys/!

Implicit through table joins should be appeared before user supplied joins

Fix that an ActiveRecord::RecordNotUnique error would be raised when saving rich-text content with the same file attached multiple times.

typo change

Fix: DummyCompiler embeds invalid YAML content

Fix database loading when ERB is single line ternary

Backport 378dd7a4.

https://github.com/rails/rails/blob/65bdd6ad085a02b976cd36f135c2a5ffb522e5a0/activesupport/CHANGELOG.md

Fix eager loading associations with string joins not to raise NoMethodError

To avoid word wrap in the rendered guide.

Don't track implicit `touch` mutation

Update the sqlite db yaml template to match other templates and mention proper supported version

According to https://www.npmjs.com/.

Only build middleware proxy when instrumentating