refactor(pubsub): use the clock class instead of a lambda

[alevenberg]

Part of #13298

4/4 in a chain

1. refactor(pubsub): create shared helper tracing functions #13377
2. impl(pubsub): add a link to the extend span #13378
3. impl(pubsub): use factory to create pull lease manager #13379
4. refactor(pubsub): use the clock class instead of a lambda  #13389

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6a938ab) 93.09% compared to head (dc5e215) 93.10%.
Report is 9 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #13389   +/-   ##
=======================================
  Coverage   93.09%   93.10%           
=======================================
  Files        2164     2164           
  Lines      188858   188857    -1     
=======================================
+ Hits       175824   175826    +2     
+ Misses      13034    13031    -3     

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