Use plain assert in assert_changes to avoid MT6 refutes

Fix typoes on ActionDispatch::HTTP::FilterParameters

Correctly kill the server started with ujs test

`Kernel.#spawn` execute command via the shell if contains shell
metacharacters in the command.
In that case, return value of `spawn` is pid of the shell, not the server.
Therefore, just killing the pid will leave the process of server.

In order to correctly kill the server, send a signal to the process
group, not the process.

Allow `ConcurrentTransactionTest` can run with Oracle enhanced adapter

returns true

Not only postgresql or mysql2 adapter, Oracle enhanced adapter
whose default isolation level is read commited, passes these two test cases.

`ConcurrentTransactionTest#test_transaction_per_thread`
`ConcurrentTransactionTest#test_transaction_isolation__read_committed`

```ruby
$ ARCONN=oracle bin/test test/cases/transactions_test.rb:961 -v
Using oracle
Run options: -v --seed 18865

ConcurrentTransactionTest#test_transaction_per_thread = 0.98 s = .

Finished in 1.061036s, 0.9425 runs/s, 5.6549 assertions/s.

1 runs, 6 assertions, 0 failures, 0 errors, 0 skips
```

```ruby
$ ARCONN=oracle bin/test test/cases/transactions_test.rb:979 -v
Using oracle
Run options: -v --seed 13341

ConcurrentTransactionTest#test_transaction_isolation__read_committed = 1.85 s = .

Finished in 1.928637s, 0.5185 runs/s, 10.3700 assertions/s.

1 runs, 20 assertions, 0 failures, 0 errors, 0 skips
$
```

Also, regardless it is a file based or memory based these tests could fail with SQLite3Adapter.
(Extra CR added to make lines shorter)

```ruby
$ ARCONN=sqlite3 bin/test test/cases/transactions_test.rb:961 -v
Using sqlite3
Run options: -v --seed 18815

ConcurrentTransactionTest#test_transaction_per_thread = /home/yahonda/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/gems/sqlite3-1.3.13/lib/sqlite3/statement.rb:108:in `step':
SQLite3::BusyException: database is locked: UPDATE "topics" SET "approved" = ?, "updated_at" = ? WHERE "topics"."id" = ? (ActiveRecord::StatementInvalid)
```

```ruby
$ ARCONN=sqlite3 bin/test test/cases/transactions_test.rb:979 -v
Using sqlite3
Run options: -v --seed 25520

ConcurrentTransactionTest#test_transaction_isolation__read_committed = 0.12 s = E
/home/yahonda/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/gems/sqlite3-1.3.13/lib/sqlite3/statement.rb:108:in `step':
SQLite3::BusyException: database is locked: UPDATE "developers" SET "salary" = ?, "updated_at" = ?, "updated_on" = ? WHERE "developers"."id" = ? (ActiveRecord::StatementInvalid)
```

Change output log about skipping instalation of Active Storage

Merge pull request #31092 from bogdanvlviv/remove-redundant-passing-skip-active-storage-in-test-cases

Remove redundant passing --skip-active-storage in test cases

Using of "`" is preferable over "'" to express console command in output log

These were added in #30101, after #31084 it became redundant.

`through_reflection` and `source_reflection` are used only in the class.

Use released `redis-namespace` instead of master version

The `redis-namespace` 1.6.0 includes redis-rb 4.0 support.

Fix output of `select_tag` with `include_blank: true` [ci skip]

Merge pull request #31084 from y-yagi/do_not_run_active_storage_install_when_bundle_install_is_skipped

Do not run active storage install when bundle install is skipped

Since #24923, if use `select_tag` with `include_blank: true`, an empty
label is added.

Since isolation application is generated with the `--skip-gemfile`
option, so `active_storage:install` is not executed.

In order to execute the `rails` command, need to run bundle install in
advance.
Therefore, if skipped bundle install, `rails` command may fail and
should not do it.

Seeing the previously issued PRs about it, we can avoid the `nil`
comparisons that can happen in `assert_changes` by using plain `assert`
calls.

This is to avoid a deprecation warning about comparing `nil` values in
`assert_equal` for Minitest 5 and a crash in Minitest 6.

You can see the preparations done in [`assert_equal`][ae]. You can also
see that [`assert`][a] does not care about `nil`s.

[ae]: https://github.com/seattlerb/minitest/blob/ca6a71ca901016db09a5ad466b4adea4b52a504a/lib/minitest/assertions.rb#L159-L188
[a]: https://github.com/seattlerb/minitest/blob/ca6a71ca901016db09a5ad466b4adea4b52a504a/lib/minitest/assertions.rb#L131-L142

Fix comment in `check_class_collision` [ci skip]

`ScaffoldBase` was changed to `ResourceHelpers` by 0efedf2a.

Prevent extra string allocations when no 'rel' arg passed

Add cases to test combining validation conditions

Fix `bin/rails db:migrate` with specified `VERSION`

Closes #31073.

`associated_records_by_owner` had returned customizing result before
calling `associate_records_to_owner` for through association subclasses.
Since #22115, `associate_records_to_owner` is called in the method and
not returned owner and result pairs. Removing the method will reduce
method call and block call nesting.

Execute `ConfirmationValidator` validation when `_confirmation`'s value is `false`

 - Test condition that is defined by array of conditions
 - Test condition that is defined by combining :if and :unless
 - Test local condition that is defined by :if
 - Test local condition that is defined by :unless

See http://edgeguides.rubyonrails.org/active_record_validations.html#combining-validation-conditions

Ensure that `bin/rails db:migrate` with specified `VERSION` reverts
all migrations only if `VERSION` is `0`.
Raise error if target migration doesn't exist.

Provide initialization of Active Storage

Make `assert_recognizes` to traverse mounted engines

Handle Timeout.timeout in rails queries