Why this change?
We support a `USE_TURBO` environment variable which tells the
`docker:test` rake task to run rspec tests in parallel. However, this
currently does not apply to system tests.
What does this change do?
This commit runs system specs for both core and plugins using
`./bin/turbo_rspec` when the `USE_TURBO` environment is present. Note
that when running system specs, we will only spawn X number of test
processes where X is half the number of available CPU cores. This is
done because we have to leave CPU resources for the chrome processes
that will be created.
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