Fix goroutine leak in cmd/agent/app/reporter/grpc

[akagami-harsh]

Which problem is this PR solving?

• part of Enable and enforce goroutine leak checks in tests #5006

Description of the changes

• fixed goroutine leaks in cmd/agent/app/reporter/grpc and also added a goleak check

How was this change tested?

• go test

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test

[github-actions]

Test Results

2 053 tests  ±0   2 043 ✅ ±0   1m 8s ⏱️ -1s
  219 suites ±0      10 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit 4db2698. ± Comparison against base commit e85c8fb.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e85c8fb) 95.62% compared to head (4db2698) 95.60%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5075      +/-   ##
==========================================
- Coverage   95.62%   95.60%   -0.02%     
==========================================
  Files         314      314              
  Lines       18296    18302       +6     
==========================================
+ Hits        17495    17498       +3     
- Misses        642      644       +2     
- Partials      159      160       +1     

Flag	Coverage Δ
cassandra-3.x	25.59% <ø> (ø)
cassandra-4.x	25.59% <ø> (ø)
elasticsearch-5.x	19.87% <ø> (ø)
elasticsearch-6.x	19.87% <ø> (ø)
elasticsearch-7.x	19.99% <ø> (-0.02%)	⬇️
elasticsearch-8.x	20.10% <ø> (ø)
grpc-badger	19.49% <ø> (-0.02%)	⬇️
kafka	14.10% <ø> (ø)
opensearch-1.x	20.01% <ø> (ø)
opensearch-2.x	20.01% <ø> (ø)
unittests	93.29% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[yurishkuro]

Thanks!