fix(flow): fix invalid ellipseText regex

[aloisklink]

📑 Summary

Fixes an invalid regex that was causing flowcharts to freeze if there was an ellipse node that had a ( character in the text.

E.g.

The following diagram freezes in Mermaid v10.6.0

```mermaid
flowchart
  X(- My Text (
```

Resolves #4964

📏 Design Decisions

I'm not 100% sure why this was causing a freeze (shouldn't JISON throw an error instead?), but this seems to fix the issue, so 🤷.

As a side-note, if this test freezes, it completely locks up Vitest (setting a timeout parameter doesn't seem to help). We could instead run this test in a child_process, but since creating a child process is pretty slow normally, so it's probably not worth slowing down our unit tests for it.

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 💻 have added necessary unit/e2e tests.
• 📓 have added documentation. Make sure MERMAID_RELEASE_VERSION is used for all new features.
• 🔖 targeted develop branch

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[codecov]

Codecov Report

Merging #5016 (172d90e) into develop (ff4d68f) will increase coverage by 0.34%.
Report is 17 commits behind head on develop.
The diff coverage is 66.66%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5016      +/-   ##
===========================================
+ Coverage    79.37%   79.72%   +0.34%     
===========================================
  Files          164      164              
  Lines        13815    13820       +5     
  Branches       693      693              
===========================================
+ Hits         10966    11018      +52     
+ Misses        2700     2653      -47     
  Partials       149      149              

Flag	Coverage Δ
e2e	85.67% <66.66%> (+0.43%)	⬆️
unit	42.94% <ø> (ø)

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

Files	Coverage Δ
packages/mermaid/src/diagrams/flowchart/flowDb.js	83.92% <66.66%> (+1.87%)	⬆️

... and 6 files with indirect coverage changes

[knsv]

LGTM, Thanks for adding the test