Feat: add an annotation for the addon

[suwliang3]

Description of your changes

🤖 Generated by Copilot at 0c1b191

Summary

🏷️🧩🚀

Add a new annotation system.addon to helm charts of addons in the addon package. This enables the system to recognize and handle addons differently from regular helm charts.

addon package grows
adding annotation key
system.addon - spring

Walkthrough

• Add system.addon annotation to helm chart metadata of addons (link)
  • Use the constant addonSystemRequirement from the addon package as the annotation key (link)
• Define the constant addonSystemRequirement in the addon package (link)
  • The constant is used in the utils.go file to add the annotation to addons (link)

Fixes #6255

I have:

• Read and followed KubeVela's contribution process.
• Related Docs updated properly. In a new feature or configuration option, an update to the documentation is necessary.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

Special notes for your reviewer

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.05% ⚠️

Comparison is base (9c57c09) 66.30% compared to head (5e0ac1d) 66.26%.

❗ Current head 5e0ac1d differs from pull request most recent head 827e535. Consider uploading reports for the commit 827e535 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6256      +/-   ##
==========================================
- Coverage   66.30%   66.26%   -0.05%     
==========================================
  Files         183      183              
  Lines       23950    23951       +1     
==========================================
- Hits        15880    15870      -10     
- Misses       6509     6523      +14     
+ Partials     1561     1558       -3     

Flag	Coverage Δ
core-unittests	55.29% <100.00%> (+0.01%)	⬆️
e2e-multicluster-test	31.00% <0.00%> (-0.12%)	⬇️
e2etests	32.91% <ø> (-0.08%)	⬇️

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Files Changed	Coverage Δ
pkg/addon/versioned_registry.go	80.11% <ø> (ø)
pkg/addon/utils.go	68.66% <100.00%> (+0.94%)	⬆️

... and 9 files with indirect coverage changes

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[wonderflow]

generally LGTM, please add some test cases