`use_color` was defaulted to 'on' and only turned off when it was
decided the terminal didn't support this. This was the wrong
way to go about things, since that test only ran for Linux/Mac other
operating systems would get color formatting regardless if they
supported it.
The new default is `off` until the platform specific code inside
`CLG_ctx_output_set` turns it on after running some sanity checks.
This fix was part of the review of D8848 but deserved its on commit
Reviewed By: campbellbarton
359acad5e4