fix(abc:st): fix invalid toTop when scroll is set

[cipchk]

• close When use ST Scroll, STPage toTop not working ng-alain#2056

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ng-alain/delon/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?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #1311 (538f882) into master (4ef5a59) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1311      +/-   ##
==========================================
- Coverage   95.88%   95.88%   -0.01%     
==========================================
  Files         269      269              
  Lines        8269     8268       -1     
  Branches     1502     1502              
==========================================
- Hits         7929     7928       -1     
  Misses        157      157              
  Partials      183      183              

Impacted Files	Coverage Δ
packages/abc/st/st.component.ts	99.55% <100.00%> (-0.01%)	⬇️

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