impl(pubsub): update last extension for successful extend

[PhongChuong]

Lease state propagate extension results back to LeaseLoop using by the LeaseEvent ExtendCompleted and ExtendCompletedEO. The result are used to update the last extension value in the lease state. We also discard previously extensions that are not complete by the next lease extension interval.

An alternative solution was to use channels (either a new channel or the existing confirmed channel) but it would not allow us to easily discard old extension results from previous lease extension intervals.

Fixes: #5048

[codecov]

Codecov Report

❌ Patch coverage is 97.77778% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.76%. Comparing base (8ca77e7) to head (d6ce1c9).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/pubsub/src/subscriber/lease_state.rs	95.34%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5530   +/-   ##
=======================================
  Coverage   97.76%   97.76%           
=======================================
  Files         218      218           
  Lines       49498    49571   +73     
=======================================
+ Hits        48390    48462   +72     
- Misses       1108     1109    +1     

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