Fix data race in keyspace event watcher

[GuptaManan100]

Description

In a recent PR of mine #16655, I accidentally introduced a data race. We shouldn't be accessing internal elements of a keyspace state without locking the mutex.

Related Issue(s)

Checklist

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Deployment Notes

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.93%. Comparing base (e89f684) to head (e30f73e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16683      +/-   ##
==========================================
- Coverage   68.93%   68.93%   -0.01%     
==========================================
  Files        1564     1564              
  Lines      201371   201375       +4     
==========================================
- Hits       138821   138810      -11     
- Misses      62550    62565      +15     

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