fix: disable ANSI color seq for debug logs

[cristiand391]

What does this PR do?

Disable ANSI color sequences when writing the commad-stdout log using the new env vars: forcedotcom/sfdx-core#1204

[16:52:24.322] �[90mTRACE�[39m (sf-startup): �[36mCreated 'sf-startup' child logger instance�[39m
[16:52:24.323] �[90mTRACE�[39m (sf:oclif:find-root:root-plugin): �[36mCreated 'sf:oclif:find-root:root-plugin' child logger instance�[39m
...

TODO:

• add test instructions, I think these changes don't work yet when linking the plugin because the top-level logger being passed is still using the old sfdx-core, should be tested with local sf repo and deduping core.

What issues does this PR fix or reference?