fix: destroy custom label before render

[NewByVector]

Description

Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Enhancement (changes that improvement of current feature or performance)
• Refactoring (changes that neither fixes a bug nor adds a feature)
• Test Case (changes that add missing tests or correct existing tests)
• Code style optimization (changes that do not affect the meaning of the code)
• Docs (changes that only update documentation)
• Chore (changes that don't modify src or test files)

Self Check before Merge

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[x6-bot]

@NewByVector Please provide us with more info about this pull request.

[codecov]

Codecov Report

Attention: 17 lines in your changes are missing coverage. Please review.

Comparison is base (8169d42) 10.37% compared to head (be5a4a0) 10.37%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4146   +/-   ##
=======================================
  Coverage   10.37%   10.37%           
=======================================
  Files         180      180           
  Lines       10550    10550           
  Branches     2569     2569           
=======================================
  Hits         1095     1095           
  Misses       9366     9366           
  Partials       89       89           

Flag	Coverage Δ
x6	10.37% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
packages/x6/src/graph/options.ts	17.64% <ø> (ø)
packages/x6/src/view/edge.ts	1.12% <0.00%> (ø)