perf : optimizations to send event logging performance

[mzydmer]

Small improve performance

• [Minimizing the usage of instanceof checks ]

• [uses a combined isinstance check for both NullAction and NullObservation ]

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes are missing coverage. Please review.

❗ No coverage uploaded for pull request base (main@242c4a0). Click here to learn what that means.

Files	Patch %	Lines
opendevin/server/agent/agent.py	0.00%	2 Missing ⚠️

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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1635   +/-   ##
=======================================
  Coverage        ?   61.12%           
=======================================
  Files           ?       92           
  Lines           ?     3717           
  Branches        ?        0           
=======================================
  Hits            ?     2272           
  Misses          ?     1445           
  Partials        ?        0           

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