Why is this change required?
By default, `RSpec` comes with a `--profile=[COUNT]` option as well but
enabling that option means that the entire test suite needs to be
executed. This does not work so well for `turbo_rspec` which splits our
test files into various "buckets" for the tests to be executed in
multiple processes. Therefore, this commit adds a similar
`--profile=[COUNT]` option to `turbo_rspec` but will only profile the
tests being executed. Examples:
`LOAD_PLUGINS=1 bin/turbo_rspec --profile plugins/*/spec/system`
or
`LOAD_PLUGINS=1 bin/turbo_rspec --profile=20 plugins/*/spec/system`
