fix(#19740) - change GL dropdown selection color

What does this MR do?

GL dropdown selection color too light, this MR make the GL dropdown selection color match what it looks like in form selection elements.

It looked like the background color for the dropdown elements on hover was using the hover background color for table rows. At least that's what I had extrapolated (perhaps erroneously). So I set the background color to be the same as was found in the selection scss file.

Are there points in the code the reviewer needs to double check?

Yes! Though the background could be manipulated without any weird code, I ended up putting an !important tag for the hover text color. I noticed !important tags in other places in the CSS so I made an assumption about GL's preferences on using it. If someone would be able to point me in the direction where I might be able to make the update without using an !important tag then I'd be glad to change it!

Why was this MR needed?

Brought up in issue #19740 (closed). Though there was no discussion on the issue, so it might not even be a change your team is considering.

What are the relevant issue numbers?

#19740 (closed)

Screenshots (if relevant)

Here is what the dropdown selection color looks like on the GL site:

Here is what the form selection elements look like on the GL site (taken from new issue form):

Here is what this MR does to the dropdowns:

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

Thanks for reading this! I understand if the criteria isn't right or if this MR is just totally off base. I appreciate any feedback you can give meeeeeee