[ISSUE #9377]fix 'send trace data can fail if shutdown producer immediately'

[kingkh1995]

Which Issue(s) This PR Fixes

Fixes #9377

Brief Description

1. shutdown traceExecutor gracefully when shutdown AsyncTraceDispatcher;
2. optimize flush(), no need to check size of appenderQueue, submitted tasks will be executed.

How Did You Test This Change?

test

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 48.11%. Comparing base (6819b4d) to head (8317860).
⚠️ Report is 266 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #9378      +/-   ##
=============================================
- Coverage      48.15%   48.11%   -0.05%     
+ Complexity     12153    12142      -11     
=============================================
  Files           1323     1323              
  Lines          93441    93438       -3     
  Branches       12009    12007       -2     
=============================================
- Hits           44998    44954      -44     
- Misses         42878    42919      +41     
  Partials        5565     5565              

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[kingkh1995]

@yuz10