Eliminate warning about setting timestamps in the ecephys stream

[h-mayorquin]

This is something that @CodyCBakerPhD requested from me a while ago and I forgot to do.

That warning is meant for people who will use this in preprocessing (and I think it should be triggered in a different place) but this should suppress this uninformative warning in our use case.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.32%. Comparing base (1498a50) to head (a24fe04).
Report is 61 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1060   +/-   ##
=======================================
  Coverage   90.32%   90.32%           
=======================================
  Files         129      129           
  Lines        7996     7996           
=======================================
  Hits         7222     7222           
  Misses        774      774           

Flag	Coverage Δ
unittests	90.32% <100.00%> (ø)

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Files with missing lines	Coverage Δ
...erfaces/ecephys/baserecordingextractorinterface.py	92.78% <100.00%> (ø)
...nterfaces/ecephys/basesortingextractorinterface.py	79.79% <100.00%> (ø)