perf: reduce fixed sleeps in test mode

[vringar]

Summary

• Reduce the 2s post-CommandSequence drain sleep to 0.1s when manager_params.testing is True
• Reduce the 5s FinalizeCommand sleep to 0.1s when manager_params.testing is True
• Production behavior unchanged

These are stopgap sleeps (documented as support for #135) that add ~7s per visit in tests.

Stacked on #1126.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.31%. Comparing base (f286084) to head (d8a34a1).

Files with missing lines	Patch %	Lines
openwpm/browser_manager.py	0.00%	2 Missing ⚠️
openwpm/commands/browser_commands.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@                      Coverage Diff                       @@
##           refactor/storage-interface    #1127      +/-   ##
==============================================================
+ Coverage                       40.54%   43.31%   +2.77%     
==============================================================
  Files                              39       39              
  Lines                            3611     3613       +2     
==============================================================
+ Hits                             1464     1565     +101     
+ Misses                           2147     2048      -99     

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[vringar]

Folded into #1128 — sleep reductions only make sense alongside the event-driven replacement.