fix(module:tooltip): invalid custom color arrow style

[Ludidi]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

invalid custom color arrow style: https://stackblitz.com/edit/angular-tf7gjo?file=src%2Fapp%2Fapp.component.ts

What is the new behavior?

fix background-color，normal display style

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[zorro-bot[bot]]

This preview will be available after the AzureCI is passed.

[codecov[bot]]

Codecov Report

Merging #7581 (c540a94) into master (f18149a) will decrease coverage by 0.00%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7581      +/-   ##
==========================================
- Coverage   91.74%   91.73%   -0.01%     
==========================================
  Files         502      502              
  Lines       16756    16756              
  Branches     2757     2757              
==========================================
- Hits        15372    15371       -1     
- Misses       1050     1051       +1     
  Partials      334      334              

Impacted Files	Coverage Δ
components/core/util/text-measure.ts	92.10% <0.00%> (-0.88%)	:arrow_down:

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[simplejason]

All style files are synced from ant-design(except patch.less) and we won't modify thses style files individually, you can overwrite it in your own project or commit to ant-design :) Thanks.