fix(ui): fix washed out dropdown colors in dark mode

[JustasMonkev]

This patch enforces a dark-mode-friendly background and text color on the dropdown elements.

previously

with the fix

References #33931

[github-actions]

Test results for "tests 1"

7 flaky

⚠️ [firefox-page] › page/page-evaluate.spec.ts:403:3 › should throw for too deep reference chain @firefox-ubuntu-22.04-node18
⚠️ [webkit-library] › library/browsertype-connect.spec.ts:343:5 › launchServer › should throw when calling waitForNavigation after disconnect @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › library/defaultbrowsercontext-1.spec.ts:22:3 › context.cookies() should work @smoke @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › library/inspector/cli-codegen-test.spec.ts:112:5 › should generate routeFromHAR with --save-har and --save-har-glob @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › library/proxy.spec.ts:93:11 › should proxy local network requests › by default › loopback address @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › library/proxy.spec.ts:178:3 › should exclude patterns @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › page/page-set-input-files.spec.ts:205:3 › should upload multiple large files @webkit-ubuntu-22.04-node18

37473 passed, 650 skipped
✔️✔️✔️

Merge workflow run.

[agg23]

Thank you for the fix!