perf(module:back-top): do not run change detection if there are no nzClick listeners

[arturovt]

PR Checklist

• 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

[x] Refactoring (no functional changes, no api changes)

Does this PR introduce a breaking change?

[ ] Yes
[x] No

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #7179 (a2bd0bd) into master (3c3eac9) will decrease coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #7179      +/-   ##
==========================================
- Coverage   91.76%   91.72%   -0.05%     
==========================================
  Files         486      486              
  Lines       15939    15944       +5     
  Branches     2590     2592       +2     
==========================================
- Hits        14626    14624       -2     
- Misses       1002     1010       +8     
+ Partials      311      310       -1     

Impacted Files	Coverage Δ
components/back-top/back-top.component.ts	91.66% <100.00%> (+0.75%)	⬆️
components/table/src/table/tr-measure.component.ts	86.36% <0.00%> (-13.64%)	⬇️
components/table/src/table/tbody.component.ts	88.88% <0.00%> (-11.12%)	⬇️
...ts/table/src/table/table-inner-scroll.component.ts	79.41% <0.00%> (-4.42%)	⬇️
components/table/src/table-style.service.ts	96.55% <0.00%> (+1.72%)	⬆️

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[simplejason]

LGTM

[simplejason]

After the PR approved, I found some conflicts, so I will rebase with master and commit the changes to this branch :)