fix(map): disable resize handles on Centreon link edges

[vuntz]

Description

Fixes: MON-190970

Disable custom shape handles and the width input in the Format panel for Centreon link edges (type="LINK"). The backend does not persist geometry changes for edges (width/height are only extracted for vertices in MxCell.toGraphics()), so any resize modifications made in the editor are silently lost on save.

Two changes:

• Shapes.js: Return null from createCustomHandles for Centreon links, preventing the orange diamond manipulation handles from appearing (both on init and after edge interactions like terminal moves)
• Format.js: Hide the "Width" input in the Arrange panel for Centreon links that use flexArrow/link shapes

Type of change

• Patch fixing an issue (non-breaking change)
• New functionality (non-breaking change)
• Breaking change (patch or feature) that might cause side effects breaking part of the Software

Target serie

• 23.10.x
• 24.04.x
• 24.10.x
• 25.10.x
• master

How this pull request can be tested ?

1. Open the MAP editor
2. Add a metric link (or any Centreon link: SIMPLE, METRIC, STATUS)
3. Select the link — verify no orange diamond resize handles appear
4. Check the Format/Arrange panel — verify no "Width" input is shown for the link
5. Move the edge terminals — verify handles don't reappear after interaction
6. Verify that standard draw.io edges (non-Centreon connectors) still show their normal handles

Checklist

• I have followed the coding style guidelines provided by Centreon
• I have commented my code, especially new classes, functions or any legacy code modified.
• I have commented my code, especially hard-to-understand areas of the PR.
• I have rebased my development branch on the base branch (master, maintenance).

Summary by Aikido

Security Issues: 0	Quality Issues: 0	Resolved Issues: 0

🐛 Bugfixes

• Disabled custom resize handles for Centreon link edges in Shapes.js
• Hidden Width input for Centreon flexArrow/link edges in Format.js

^{More info}