Removing background colour

[connormeredith]

What does this PR do? (please provide any background)

I've removed @background-color from the _colors.less file as per @jodiedoubleday's request. I've also updated the troubleshooting document with an issue I encountered.

What tests does this PR have?

None.

How can this be tested?

It's not used within the toolkit so just make sure I haven't done a bad.

Screenshots / Screencast

None.

What gif best describes how you feel about this work?

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• [x] I have checked our general contributing document and the project specific contributing document (if present) and I'm happy for this to be reviewed.

  Reviewers

Review 1

• [x] :+1:

Review 2 *

• [x] :+1:

Review 3 (optional)

• [ ] :+1:

By adding a +1 you are confirming you have...

• Witnessed the work behaving as expected (this could be on the author's machine or screencast).
• Checked for coding anti-patterns.
• Checked for appropriate test coverage.
• Checked all the tests are passing.

* for HX this review must be completed by an SE, SA or Project Guru

[jodiedoubleday]

:shipit:

[elliottcrush]

:mag:

[elliottcrush]

All good :+1: