this removes the following warning:

```
DEPRECATION: `config.poll_interval = 0.5` will be removed in Sidekiq 4. Please update to `config.average_scheduled_poll_interval = 0.5`.
```

When `#perform_later` is called the locale isn't stored on the
queue, which results in a locale reset when the job is performed.

An example of the problem:

    I18n.locale = 'de'
    HelloJob.perform_now # german message, correct

but

    I18n.locale = 'de'
    HelloJob.perform_later # english message, incorrect

This PR attaches the current I18n.locale to every job during the
serialization process. It is then restored during deserialization
and used to perform the job with the correct locale.

It falls back to the default locale if no serialized locale is
found in order to provide backward compatibility with previously
stored jobs. It is not necessary to clear the queue for the update.

Further work to provide provider_job_id for queue adapters.

See #19498

setup gets called from the initializer, so it happens more than once in
a test run. Trying to drop the database again after the first process is
connected is.. ineffective. And entirely pointless.

Instead, defer creating the database to start_workers -- which only
happens once, right before we start doing anything real.

* Don't swallow output -- if there is any, it's probably useful
* Wait for the process to finish
* Use IPC instead of a sleep
* No need for a pidfile

Requiring sidekiq/testing changes stuff, so we need to counteract that
after we do so.

And given its potential to confuse things, let's do it up front, at a
predictable point.

Sidekiq::CLI#boot_system require "#{dummy_app_path}/config/environment.rb".
But this file has already been required in'test/support/integration/helper.rb'.
This patch will change to use Sidekiq::Launcher directly.

I’m renaming all instances of `use_transcational_fixtures` to
`use_transactional_tests` and “transactional fixtures” to
“transactional tests”.

I’m deprecating `use_transactional_fixtures=`. So anyone who is
explicitly setting this will get a warning telling them to use
`use_transactional_tests=` instead.

I’m maintaining backwards compatibility—both forms will work.
`use_transactional_tests` will check to see if
`use_transactional_fixtures` is set and use that, otherwise it will use
itself. But because `use_transactional_tests` is a class attribute
(created with `class_attribute`) this requires a little bit of hoop
jumping. The writer method that `class_attribute` generates defines a
new reader method that return the value being set. Which means we can’t
set the default of `true` using `use_transactional_tests=` as was done
previously because that won’t take into account anyone using
`use_transactional_fixtures`. Instead I defined the reader method
manually and it checks `use_transactional_fixtures`. If it was set then
it should be used, otherwise it should return the default, which is
`true`. If someone uses `use_transactional_tests=` then it will
overwrite the backwards-compatible method with whatever they set.

* This allows for easier reading, since those are two words, so they should be
  split by _
Signed-off-by: NJeroen van Baarsen <jeroenvanbaarsen@gmail.com>

ref: https://github.com/rails/rails/pull/18763#issuecomment-72349769

Use redis protocol

* .connect on a Redis connection wasn't valid
* Reset logger after we're done testing for redis connection to avoid
  "closed stream" error when starting server for real from a fork

In passing, avoid a blind retry in QC: instead, just fix the problem.