Fix: transcoders wait forever on orchestrator restart

[stronk-dev]

What does this pull request do?

Fixes a bug where transcoders would wait forever on a orchestrator restart if they had a previous transcoding session. Fix simply moves the wg.Add(1) call so that the wait group is able to reach 0 again

Specific updates

My thinking is the bug got introduced in this commit: a1fb761#diff-0db7e4513a2e3eb16dedb22ed6a0920e6648e62733004c11dc0ed8a19f314464 so 0.5.34 should still be good, anything after that should have this issue

How did you test each of these updates

Ran a split O/T setup on my main Orchestrator and rebooted it while the connected transcoders were busy transcoding or recently completed a transcoding session. Repeated a couple of times and my transcoders reconnected successfully every time

Fix ran in a pool environment in production, all T's were able to restart themselves gracefully when restarting the O numerous times over the past few days!

Does this pull request close any open issues?

Fixes #2704

[codecov]

Codecov Report

Merging #2705 (0c7e4a3) into master (cf95f00) will decrease coverage by 0.00589%.
The diff coverage is 0.00000%.

@@                 Coverage Diff                 @@
##              master       #2705         +/-   ##
===================================================
- Coverage   56.35194%   56.34605%   -0.00589%     
===================================================
  Files             88          88                 
  Lines          19128       19130          +2     
===================================================
  Hits           10779       10779                 
- Misses          7761        7763          +2     
  Partials         588         588                 

Impacted Files	Coverage Δ
cmd/livepeer_cli/wizard_stats.go	0.00000% <0.00000%> (ø)
server/ot_rpc.go	35.34483% <0.00000%> (ø)

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Impacted Files	Coverage Δ
cmd/livepeer_cli/wizard_stats.go	0.00000% <0.00000%> (ø)
server/ot_rpc.go	35.34483% <0.00000%> (ø)

[cyberj0g]

Nice catch! LGTM!

[eliteprox]

Looks like this PR still needs to be merged