Follow up to #16613

Since we want this flag to be enabled anytime we are running the tests
under JRuby, let's enable this at the Rakefile level so people get the
performance boost on their local checkout.

Moreover, we avoid having to update this particular line anytime the
option changes on the JRuby side.

The only drawback is that we have to define it in every Rakefile but
there's no big deal, this is already the case for other options.
Merge pull request #17088 from robin850/jruby-dev

Follow up to #16613
Add documentation on Active Job.

This adds documentation for the Active Job API. It includes
documentation on how to configure the queue_adapter, and how to create
new jobs. It adds links to the various other sections of the Active Job
documentation.
Merge pull request #17068 from mokhan/update-active-job-documentation

[ci-skip] Update Active Job API documentation
Disallow appended newlines when parsing as integer

\Z allows appended newlines where \z does not.
Merge pull request #17148 from mgenereu/patch-1

Disallow appended newlines when parsing as integer
[ci skip] add `test:jobs` task to testing guide
Fix style for rescue responses doc [ci skip]

 * Change 'Any ***s that are...' to 'Any *** that is...'
 * Fix style for default rescue_responses setting

This is a follow-up commit to:

 * https://github.com/rails/rails/pull/17076
 * https://github.com/yuki24/rails/commit/89b8836f2470c689f6b7d52cab3a418bb63aef26
Merge pull request #17151 from y-yagi/patch-1

[ci skip] add `test:jobs` task to testing guide
Merge pull request #17153 from yuki24/fix-doc-format-for-rescue-responses

[Railsguides] Fix style for rescue responses doc [ci skip]
Revert "Fix style for rescue responses doc [ci skip]"

Reason: There is a wrong newline, a typo, and the change
to singular is not good.

This reverts commit d76380cf1ccec7ffeff19827ae9b6d9b71327418.
minor fixes in the configuring guide [ci skip]