fix: remove stable from active branches for models-as-a-service

The stable branch is no longer actively used for models-as-a-service
upstream. Removing it prevents unnecessary CVE fix attempts against
a stale branch.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: vmrh21

workflows/cve-fixer/component-repository-mappings.json

@@ -7,7 +7,6 @@
           "type": "midstream",
           "default_branch": "main",
           "active_branches": [
-            "stable",
             "rhoai",
             "v0.1.x"
           ],