MID-10957 Filter deprecated sync action choices

[kay1313]

Summary

Fixes MID-10957: selecting the deprecated synchronization action Unlink in the resource object type editor could cause an internal server error.

The action dropdown was offering deprecated synchronization action containers. When Unlink was selected, wrapper creation skipped the deprecated newly-created item and returned null; the dropdown code then dereferenced the missing wrapper and failed with a NullPointerException.

Changes

• Filter deprecated container definitions out of ContainersDropDownPanel choices by default.
• Keep already-selected deprecated containers visible, so legacy configuration can still be opened/migrated safely.
• Add a defensive null check around newly-created item wrappers.
• Remove the raw container from the underlying value if wrapper creation is skipped.
• Add regression tests for deprecated synchronization action dropdown behavior and the null-wrapper path.

Testing

• Added tests covering:
  • deprecated Unlink is not offered as a new dropdown choice;
  • existing legacy empty Unlink configuration opens safely;
  • legacy Unlink can be replaced by Synchronize;
  • skipped wrapper creation does not crash or leave a dangling container.

Manual verification:

• Confirmed Unlink is no longer offered for new/normal synchronization reactions.
• Confirmed existing resource configuration containing deprecated Unlink opens without HTTP 500.
• Confirmed existing Unlink can be changed to supported actions such as Synchronize or Link.
• Confirmed saving synchronization settings works after the change.