Flush user cache

[dlin2028]

Description

Currently, our system only allows for the invalidation of the entire user authentication cache, which can lead to numerous cache misses and inefficiencies. This change is required to allow for more precise cache management, specifically targeting stale cache entries at the individual user level without disrupting the cache state of other users

• Category: New feature
• Why these changes are required? Currently, our system only allows for the invalidation of the entire user authentication cache. This change is required to allow for more precise cache management, specifically targeting stale cache entries at the individual user level without disrupting the cache state of other users.
• What is the old behavior before changes and new behavior after changes? Previously, invalidating a user's cache required clearing the entire cache, affecting all users. The new behavior introduces an endpoint that allows for the invalidation of cache entries on a per-user basis, thereby maintaining cache integrity for other users and reducing unnecessary cache misses.

Issues Resolved

#2829

Testing

Unit testing was written in FlushCacheApiTest.java

Check List

• [X ] New functionality includes testing
• [ ] New functionality has been documented
• [ X] Commits are signed per the DCO using --signoff