The `red`, `yellow`, etc. helpers within `formatter_test.rb` are
specifically used only for testing logfile output, not console output.
Since color is not present in logfile output for SSHKit > 1.7.1, these
helpers essentially do nothing in the latest SSHKit.

Therefore, when asserting color console output, it is necessary to use
the actual ANSI color control codes, as this commit does in the
`test_log_message_levels`. Note that tests that require color must
explicitly turn on color using `airbrussh_config.color = true`.

I removed the color expectations from `test_handles_rake_tasks`, since
color is not enabled for that test.