Fix: CacheListener to use thread-safe ListenerSet for managing listeners

[solisamicus]

What this PR does:

• Replaces the map[registry.MappingListener]struct{} with a thread-safe ListenerSet for managing listeners.
• Ensures safe concurrent access by using sync.RWMutex in the ListenerSet.

Which issue(s) this PR fixes:

Fixes #2759

Special notes for your reviewer:

• This refactor improves thread safety but may require additional performance testing to ensure there is no negative impact on listener management.
• No change in external functionality, this is an internal improvement.

Does this PR introduce a user-facing change?:

NONE

[sonarqubecloud]

Quality Gate passed

Issues
23 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
4.6% Duplication on New Code

See analysis details on SonarQube Cloud