Remove unnecessary CID copying in SessionInterestManager

[gammazero]

Also reduce lock scope in some places by moving non-critical work outside of lock.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.40%. Comparing base (8d6ac57) to head (57ea06d).
Report is 1 commits behind head on main.

@@            Coverage Diff             @@
##             main     #761      +/-   ##
==========================================
- Coverage   60.40%   60.40%   -0.01%     
==========================================
  Files         245      245              
  Lines       31112    31114       +2     
==========================================
+ Hits        18792    18793       +1     
- Misses      10647    10649       +2     
+ Partials     1673     1672       -1     

Files with missing lines	Coverage Δ
...l/sessioninterestmanager/sessioninterestmanager.go	100.00% <100.00%> (ø)

... and 12 files with indirect coverage changes