Close gRPC for collecting and reporting

[pavolloffay]

Resolves #1164
and part of #773 (comment)

Signed-off-by: Pavol Loffay [email protected]

[codecov]

Codecov Report

Merging #1187 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #1187   +/-   ##
======================================
  Coverage     100%    100%           
======================================
  Files         157     157           
  Lines        7101    7107    +6     
======================================
+ Hits         7101    7107    +6

Impacted Files	Coverage Δ
cmd/agent/app/reporter/tchannel/collector_proxy.go	100% <100%> (ø)	⬆️
cmd/agent/app/reporter/grpc/collector_proxy.go	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 76ccd71...d28c2ff. Read the comment docs.