fix: the second app start event's sessionId

[zhu-xiaowei]

• PR title and description conform to Pull Request guidelines.

Description of changes:

1. fix the second _app_start event's sessionId

How did you test these changes?
(Please add a line here how the changes were tested)

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.50%. Comparing base (f2f80fd) to head (9daa06a).
Report is 15 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main      #70   +/-   ##
=========================================
  Coverage     86.49%   86.50%           
  Complexity      458      458           
=========================================
  Files            42       42           
  Lines          1688     1689    +1     
  Branches        154      153    -1     
=========================================
+ Hits           1460     1461    +1     
  Misses          150      150           
  Partials         78       78           

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