fix(module:graph): fix edge default style and wrong toggling group nodes

[simplejason]

PR Checklist

Please check if your PR fulfills the following requirements:

• 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?

[ ] Bugfix
[x] 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

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #6615 (df91e6d) into master (3fa6592) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #6615   +/-   ##
=======================================
  Coverage   89.91%   89.91%           
=======================================
  Files         481      481           
  Lines       15382    15382           
  Branches     2345     2345           
=======================================
  Hits        13831    13831           
  Misses        934      934           
  Partials      617      617           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3fa6592...df91e6d. Read the comment docs.

[hsuanxyz]

LGTM