livepeer/starter: remove testTranscoder flag

[emranemran]

What does this pull request do? Explain your changes. (required)
The -testTranscoder flag defaults to true which requires all hardware
transcoders to call core.TestTranscoderCapabilities() to discover
transcoding caps. Setting this flag to false is not a valid use case
anymore so this change deprecates that option.

Specific updates (required)

• Remove the use of testTranscoder flag and allow code path to always call TestTranscoderCapabilities() which it already does as the option defaults to false.

How did you test each of these updates (required)

• WIP: to be tested on GCP w/ nvidia hardware...

Does this pull request close any open issues?
Fix #2450

Checklist:

• Read the contribution guide
• make runs successfully
  [ ] All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[codecov]

Codecov Report

Merging #2472 (3f98047) into master (ed2764f) will increase coverage by 0.01727%.
The diff coverage is 0.00000%.

@@                 Coverage Diff                 @@
##              master       #2472         +/-   ##
===================================================
+ Coverage   55.06159%   55.07886%   +0.01726%     
===================================================
  Files             94          94                 
  Lines          19727       19719          -8     
===================================================
- Hits           10862       10861          -1     
+ Misses          8263        8256          -7     
  Partials         602         602                 

Impacted Files	Coverage Δ
cmd/livepeer/livepeer.go	50.00000% <ø> (-0.29940%)	⬇️
cmd/livepeer/starter/starter.go	2.35756% <0.00000%> (+0.01609%)	⬆️

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[thomshutt]

Searching across all repos, it looks like we set it to false in some of our livepeer-in-a-box configs: https://github.com/search?q=org%3Alivepeer+testTranscoder&type=code

@iameli would removing this break things?

[AlexKordic]

Tested on nvidia card with:

go run cmd/livepeer/livepeer.go --datadir=/home/alex/temp/livepeer/TEST_T1 --transcoder=true --orchSecret=foo --orchAddr="127.0.0.1:18935" --cliAddr=":17936" --nvidia=0 --v=6

[emranemran]

Perhaps this flag in livepeer-in-a-box is alright for now since it's a fork. I'm guessing we'll have to setup automerges from master in go-livepeer to livepeer-in-a-box at some point or just rebase it frequently to pick up changes. @iameli what do you think?

[cyberj0g]

I think we can merge this PR, since capability test runs only with hardware acceleration enabled. LGTM after rebasing.

[Quintendos]

@emranemran could you please close up this ticket?