Follow up to #20818.

`retrieve_connection` is passed `spec_name` instead of `klass` since #24844.

setup in ActiveSupport::LogSubscriber::TestHelper call set_logger that
will change ActionController::Base.logger to the MockLogger so that
logger will be always MockLogger

The minitest stubs were conflicting with the time travel stubs so the
travel_back method call in the teardown block was actually keeping the
time stubbed.

For those tests that use start we don't need to assert the actual order
of mime types that are returned.

This happen because this order is more about the order the mime type was
registered than the order that it is expected to it resolve.

We need to sort because we remove the json mime type in
json_params_parsing_test and add it to the end of the mime types set so
if that file runs before those tests we will have a failing test.

[Rafael Mendonça França + Lucas Hosseini]

Use notification to ensure that lazy-loaded model classes have transactions

Added :fallback_string option to Array#to_sentence

Add a note about adding CHANGELOG entries at the top of the file 

Fix failing requirement of duplicable in ParameterFilter

Mention that layout can call a Proc [ci skip]

Fix CHANGELOG grammar [ci skip]

CHANGELOG for https://github.com/rails/rails/pull/25257 [ci skip]

- Also minor weekly CHANGELOG cleanup.

Add newline between each migration in `structure.sql`

Remove unused activerecord requirement in actionpack.

Fix wrong test name

- Followup of https://github.com/rails/rails/pull/23179

Update references generation docs to exclude index

In #23179 the migration generator was changed to no longer output `index: true` for `references` migrations. This updates the migrations guide to remove `index: true` from relevant examples.

[ci skip]

add missing braces [ci skip]

Also modify to use Ruby 1.9+ syntax.

Also document return values for Proc/Symbol arguments

Eliminate extra template lookup in ActionView::Digestor

Fix broken link [ci skip]

[ci skip] fix a typo

Fix display of unsorted list in release notes of 5.0 [ci skip]

Check `request.path_parameters` encoding at the point they're set

Check for any non-UTF8 characters in path parameters at the point they're
set in `env`. Previously they were checked for when used to get a controller
class, but this meant routes that went directly to a Rack app, or skipped
controller instantiation for some other reason, had to defend against
non-UTF8 characters themselves.

Keeps schema migration inserts as a single commit, so we still get all of the
benefits of https://github.com/rails/rails/commit/42dd2336b31a8d98776d039a2b9fd7f834156a78,
but allows for easier git diff-ing. Fixes #25504.

Fix typo in mailer previews test description [ci skip]

A mailer preview test description misspelled the word configuration.
This commit updates the test description to spell the word correctly.