fix(tests): increase timeouts for CI stability in durable buffer tests

[AaronRM]

Change Summary

This change increases some of the timeouts for the durable_buffer_processor tests to improve stability on slow CI systems where pipeline initialization takes longer than expected.

What issue does this PR close?

• Addresses a flaky test reported in Flaky Test Report (automated) #2720. Includes fixes for similar tests with the same potential timing issue.

How are these changes tested?

Was able to manually reproduce the failure reported in #2720. Validated that tests pass on local runs.

Are there any user-facing changes?

No. This is a test-only change.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.08%. Comparing base (524b78d) to head (2c5caf2).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2793      +/-   ##
==========================================
- Coverage   86.09%   86.08%   -0.01%     
==========================================
  Files         694      694              
  Lines      263421   263421              
==========================================
- Hits       226789   226778      -11     
- Misses      36108    36119      +11     
  Partials      524      524              

Components	Coverage Δ
otap-dataflow	87.04% <ø> (-0.01%)	⬇️
query_abstraction	80.61% <ø> (ø)
query_engine	90.76% <ø> (ø)
otel-arrow-go	52.45% <ø> (ø)
quiver	92.25% <ø> (ø)

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