[ci skip] Fix broken url in plugins guide
Merge pull request #16472 from y-yagi/patch-1

[ci skip] Fix broken url in plugins guide
users_dont_suck_but_only_we_suck_and_only_our_tests_are_order_dependent!

Calling ActiveSupport::TestCase.i_suck_and_my_tests_are_order_dependent! in AS::TestCase makes
everyone's tests order dependent, which should never be done by the framework.
Remove old setup from AS test case

This was added back in Rails 3 on
c4a6109286909c394e8c5bfc471a1eb9de245d2b, and is not being used anymore.
CHANGELOG entry for TestCase.i_suck_and_my_tests_are_order_dependent! fix
use 'based on' instead of 'based off' [ci skip]
Nobody sucks so nobody should call this awful method name
Merge pull request #16476 from akshay-vishnoi/doc-changes

[ci skip] use "based on" or "based off of"
:bomb:
Use *_transaction methods in TransactionManager

Use `commit_transaction`/`rollback_transaction` on
`within_new_transaction` method, so they make sure they `pop` the
transaction from the stack before calling the methods `commit`/`rollback`.
Fix regression on after_commit in nested transactions.

after_commit should not run in nested transactions, however they should
run once the outermost transaction gets committed. This patch fixes the
problem copying the records from the Savepoint to its parent. So the
RealTransaction will have all records that needs to run callbacks on it.

[fixes #16425]