Revert "Merge pull request #21233 from mtsmfm/disable-referential-integrity-without-superuser-privileges"

This reverts commit eeac6151, reversing
changes made to 5c40239d.

Reason: Broke the isolated tests.
https://travis-ci.org/rails/rails/builds/188721346

* Run actionpack and actioncable tests together
* Demote ac:integration to allow_failures -- it works most of the time,
  but still fails too frequently to rely upon

ref: 72c15572

- We must use `authors` fixture with `author_addresses` because of its foreign key constraint.
- Tests require PostgreSQL >= 9.4.2 because it had a bug about `ALTER CONSTRAINTS` and fixed in 9.4.2.

2.3.2 has a known regression https://bugs.ruby-lang.org/issues/12920#note-5

All tests pass for me locally.

All tests passing locally for me:

```
195 runs, 441 assertions, 0 failures, 0 errors, 0 skips
```

- We were running into issues with old bundler versions on 4.2
  builds. So we bumped the bundler version on 4-2-stable branch in
  https://github.com/rails/rails/pull/26592.
- This commit applies same change to master as per discussion in
  https://github.com/rails/rails/pull/26592#issuecomment-254026755.

This reverts commit 2d6c14bc.

No deprecation, because it was never documented.

This reverts commit acf0bb3f, reversing
changes made to c5b766a9.

Travis can only build a commit it can clone; without any clone depth,
all branch builds error as soon as there's a newer commit present.

Allow failures until test runs are consistently stable, not hanging.

Closes #24943.
Signed-off-by: NJeremy Daer <jeremydaer@gmail.com>

Add to the matrix of Travis tests an entry that runs the Active Support
tests when `ActiveSupport.to_time_preserves_timezone = true`.

2.2.4 --> 2.2.5
2.3.0 --> 2.3.1

- Specify we want to run on latest stable ruby for mariadb

- change in runs of builds

Make mariadb? method publicly available

This reverts commit a3d085a4, reversing
changes made to e2df1c6d.

It broke the build

Uses latest precompiled JRuby so that
we don't spend time downloading versions Travis has
not already compiled. http://rubies.travis-ci.org/

Uses latest jdk: oraclejdk8
per
https://docs.travis-ci.com/user/build-environment-updates/2015-02-03/#Ruby-VM
and
https://docs.travis-ci.com/user/languages/ruby/#Supported-Ruby-Versions-and-RVM

Follows on work in https://github.com/rails/rails/pull/23927 which was reverted
https://github.com/rails/rails/commit/26fe5fa08d52384bcea09c4210e3b3baaf5e9b95

JRUBY_OPTS minimize GC, disable JIT, for max test speed
  - https://github.com/rails/rails/pull/16613
  - https://github.com/rails/rails/pull/17088

Have Rails use JRuby-compatible Rake 11.1
  - The Rake task was passing --verbose, an invalid option, to contemporary JRuby
  - https://github.com/ruby/rake/pull/120
  - https://github.com/rails-api/active_model_serializers/pull/1585
  - https://github.com/jruby/jruby/issues/3653#issuecomment-195883717

No advantage to directly mounting JRuby over installing from cache; both on S3
  - https://github.com/rails/rails/pull/23499/commits/b2d5b336b5a812009444571b22eed90777cd9a8c
  - https://github.com/rails/rails/pull/23499/commits/f4fad041b2755d81e82ee3fc66d96f334b4653db

This reverts commit ddb7be50, reversing
changes made to ee4a1462.

Reason: It is givin us a lot of timeouts in travis because JRuby 9.0.5.0
needs to be build in every run

These are green on local. Checking to see they pass on travis too!

Travis CI now select the latest patch version of Ruby automatically when
given MAJOR.MINOR version string.

Now available - https://docs.travis-ci.com/user/using-postgresql/