chore: send sample event to reporting in async destinations

[sanpj2292]

Description

As of today, the destinations operating at batch router do not posess the capability of sending sample event to the reporting service. This is making it very difficult to debug in case of failures.

We are planning add sampleEvent data for batch router(async) destinations.

Linear Ticket

Resolves INT-3077

Security

• The code changed/added as part of this pull request won't create any security issues with how the software is being used.

[codecov]

Codecov Report

Attention: Patch coverage is 84.37500% with 15 lines in your changes missing coverage. Please review.

Project coverage is 74.73%. Comparing base (b51605a) to head (750b0de).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
router/batchrouter/handle_async.go	83.69%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5396      +/-   ##
==========================================
+ Coverage   74.70%   74.73%   +0.03%     
==========================================
  Files         440      440              
  Lines       61432    61475      +43     
==========================================
+ Hits        45894    45946      +52     
+ Misses      12992    12988       -4     
+ Partials     2546     2541       -5     

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[achettyiitr]

Approving with some minor comments.