Remove tx completion tracking

[jimthematrix]

Fabric receipts are notified via golang channels, so no need to use the tracker to calculate receipt polling time

[nguyer]

Same concern applies to this one as #112 Looks like these changes were made off of that branch

[codecov-commenter]

Codecov Report

Merging #113 (332569c) into main (37e40f3) will increase coverage by 0.24%.
The diff coverage is 18.75%.

❗ Current head 332569c differs from pull request most recent head 745174f. Consider uploading reports for the commit 745174f to get more accurate results

@@            Coverage Diff             @@
##             main     #113      +/-   ##
==========================================
+ Coverage   68.21%   68.45%   +0.24%     
==========================================
  Files          47       47              
  Lines        4527     4489      -38     
==========================================
- Hits         3088     3073      -15     
+ Misses       1243     1214      -29     
- Partials      196      202       +6     

Impacted Files	Coverage Δ
cmd/debugrouter.go	0.00% <0.00%> (ø)
internal/utils/tlsutils.go	31.03% <0.00%> (ø)
internal/tx/txprocessor.go	14.58% <20.00%> (+2.95%)	⬆️
cmd/fabconnect.go	62.03% <25.00%> (-8.97%)	⬇️
internal/rest/router.go	69.36% <25.00%> (-0.64%)	⬇️
internal/fabric/client/identity.go	69.60% <45.45%> (-1.24%)	⬇️
internal/events/test_helper.go	90.90% <100.00%> (-3.04%)	⬇️
internal/events/webhooks.go	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

[jimthematrix]

the concern was addressed in the PR #112, and merged into this one.