Fixed duplicate subscribers in ActiveSupport::Subscriber

ActiveSupport::Subscriber no longer creates multiple subscribers when
you redefine a method.
Fix `Relation#delete_all` inconsistency

When relation scopes include one of `uniq`, `group`, `having` or
`offset`, the generated query ignores them and that causes unintended
records to be deleted. This solves the issue by restricting the deletion
when those scopes are present.

rails/rails#11985
Merge pull request #15071 from leafac/issues/11985

Fix `Relation#delete_all` inconsistency
Add CHANGELOG entry for #15071 [ci skip]
Merge pull request #15037 from roccoblues/fix_duplicate_activesupport_subscribers

Fixed duplicate subscribers in ActiveSupport::Subscriber

Conflicts:
	activesupport/CHANGELOG.md
Replace first person point of view on guides.

[skip ci]
Merge pull request #15143 from htanata/first_person_pronouns

Replace first person point of view on guides.
Fix typo in CHANGELOG entry for #15071
Merge pull request #15144 from leafac/fix-changelog-#15071

Fix typo in CHANGELOG entry for #15071
fixed capitalizations [ci skip]

jQuery, SQLite3 and Unicorn use these respective capitalizations pretty much everywhere else in the comment sections of the project.
Merge pull request #15145 from ShunsukeAida/capitalization

fixed capitalizations [ci skip]
fix typo [ci skip]
prefer file name instead of filename [ci skip]
Ensure :js is defined regardless of the outcome of the test.
Merge pull request #15132 from zuhao/refactor_actionpack_abstract_collector_test

Ensure :js is defined regardless of the outcome of the test.
fix symbol
Merge pull request #15147 from regonn/fix-symbol

Fix symbol at guides getting_started.md
Fix app generator test hanging.
Merge pull request #15150 from xtian/fix-railties-tests

Fix app generator test hanging.
Default config.assets.digests to true in development