[ticket/11873] Do not hash very large passwords in order to safe resources.

PHPBB3-11873
[ticket/11873] Add unit test for large password input.

The password should be rejected quite fast.

PHPBB3-11873
Merge branch 'ticket/11873' into prep-release-3.0.12

* ticket/11873:
  [ticket/11873] Add unit test for large password input.
  [ticket/11873] Do not hash very large passwords in order to safe resources.
[prep-release-3.0.12] Update changelog for 3.0.12 release.