Replace occurences of alias_method_chain with their Module#prepend counterpart

Thanks @fbernier for suggestion! <3
At this moment we can use Module#prepend in all all cases
except of Range because of the bug [1] in MRI 2.2
[1] https://bugs.ruby-lang.org/issues/10847

Strip nils out of default translations. Fixes #19419

Testing Guide: Change 'girlfriend' to 'partner'

Preserving RACK_ENV behavior.

This reverts commit 7bdc7635, reversing
changes made to 45786be5.

Preserving RACK_ENV behavior.

This reverts commit b19990c8, reversing
changes made to ac291b76.

ActionDispatch::IntegrationTest HTTP request methods will accept only
certain kwargs in the future. This test caused a deprecation warning
when running ActionPack tests. Added `params` and `headers` to fix.

Removing `#build_original_fullpath` because it is no longer
used by the Rails' source code or called in the `#call` method becasue
the previous commit now uses `fullpath` from Rack.

The method was nodoc'ed so it's safe to remove.

NOTE: I did this as a separate commit so if this does cause a problem
with engines etc reverting is easy.

In Rack, `#fullpath` checks if there is a query string and builds the
query correctly:

```
def path
  script_name + path_info
end

def fullpath
  query_string.empty? ? path : "#{path}?#{query_string}"
end
```

We can utilize this instead of manually building the fullpath because
they are the same result. This also reduces allocations in `#call`
because we don't need `build_original_fullpath` to create the paths and
query strings. We don't need to build `fullpath` twice.

[Fix Select tag Tests] Test correct use of multiple option for select tag

Fix test messages use directly true, false and nil instead of their symbol

Fixes #19389.

Updated MySQL documentation link to MySQL latest version 5.6 everywhere ...

Updated MySQL documentation link to latest version MySQL 5.6 [ci skip]

add foreign_key option to result of references column type [ci skip]

Changelog entry for removal of RACK_ENV fallback

[ci skip]

Updated MySQL documentation link for STRICT_ALL_TABLES [ci skip]

Don't fallback to RACK_ENV when RAILS_ENV is not present

3 commits were missing when we merged the PR, probably they were lost
when that branch was rebased against latest master.
This merge, contains those 3 commits.

bundle exec db:migrate rake was not working, with the new runner, before this commit

`bin/rails test` runner (rerun snippets, run tests by line, option documentation)

Add a new-line to the end of route method generated code.

ActiveRecord: Add a changelog entry for issue #17680. [ci skip]
Conflicts:
	activerecord/CHANGELOG.md

Active Record changelog pass [skip ci]

[ci skip] use true as value rather than symbol

[skip ci] Fixed typo in asset pipeline documentation