refactor: marking startTime as optional

[anandtiwary]

Description

Please include a summary of the change, motivation and context.
refactor: marking startTime as optional

Testing

Please describe the tests that you ran to verify your changes. Please summarize what did you test and what needs to be tested e.g. deployed and tested helm chart locally.

Checklist:

• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules

Documentation

Make sure that you have documented corresponding changes in this repository or hypertrace docs repo if required.

[codecov]

Codecov Report

Merging #827 (b3d4765) into main (d1428d0) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #827   +/-   ##
=======================================
  Coverage   85.44%   85.44%           
=======================================
  Files         792      792           
  Lines       16222    16222           
  Branches     1930     1930           
=======================================
  Hits        13861    13861           
  Misses       2329     2329           
  Partials       32       32           

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[github-actions]

Unit Test Results

    4 files  ±0  250 suites  ±0   14m 31s ⏱️ -51s
899 tests ±0  899 ✔️ ±0  0 💤 ±0  0 ❌ ±0 
905 runs  ±0  905 ✔️ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 9a0534a. ± Comparison against base commit d1428d0.