fix(ai): fix combined orchestrator capacity management

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What does this pull request do? Explain your changes. (required)

Fixes capacity managment for combined Orchestrator/AI workers using external containers.

Specific updates (required)

• Updates CheckAICapacity to reserve the capacity at the Orchestrator
• returns channel to release the capacity when the request is completed

How did you test each of these updates (required)

built go-livepeer and sent requests to use all capacity for combined and separate ai-workers.

Does this pull request close any open issues?

Checklist:

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

[mjh1]

nit: since we're doing a return on the line above then we can remove the else and the extra indentation

[ad-astra-video]

updated

[mjh1]

I think we can just remove this because we already track capacity with this containers map. @victorges could you check?
We don't have any call to ReserveAICapability for live video so this call to ReleaseAICapability would cause the Capacity value to always increase and never decrease.
In my PR I was planning to just set the Capacity field based to the number of entries in the containers map for live video.

[ad-astra-video]

I reworked the updates in this function to keep same functionality for live-video-to-video using local ai-worker. This allowed removing this short circuit code noted above.

[mjh1]

@ad-astra-video could you check the compile errors? https://github.com/livepeer/go-livepeer/actions/runs/14384181138/job/40335296309?pr=3389

[codecov]

Codecov Report

Attention: Patch coverage is 46.66667% with 24 lines in your changes missing coverage. Please review.

Project coverage is 30.88542%. Comparing base (bf709ec) to head (032612e).

Files with missing lines	Patch %	Lines
server/ai_http.go	0.00000%	13 Missing ⚠️
core/ai_orchestrator.go	70.00000%	8 Missing and 1 partial ⚠️
server/rpc.go	0.00000%	2 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3389         +/-   ##
===================================================
+ Coverage   30.83933%   30.88542%   +0.04609%     
===================================================
  Files            154         154                 
  Lines          45977       46012         +35     
===================================================
+ Hits           14179       14211         +32     
- Misses         30973       30975          +2     
- Partials         825         826          +1     

Files with missing lines	Coverage Δ
server/rpc.go	66.74877% <0.00000%> (-0.16481%)	⬇️
core/ai_orchestrator.go	32.30944% <70.00000%> (+1.27900%)	⬆️
server/ai_http.go	9.60961% <0.00000%> (-0.13164%)	⬇️

... and 2 files with indirect coverage changes

---

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Files with missing lines	Coverage Δ
server/rpc.go	66.74877% <0.00000%> (-0.16481%)	⬇️
core/ai_orchestrator.go	32.30944% <70.00000%> (+1.27900%)	⬆️
server/ai_http.go	9.60961% <0.00000%> (-0.13164%)	⬇️

... and 2 files with indirect coverage changes

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[ad-astra-video]

@ad-astra-video could you check the compile errors? https://github.com/livepeer/go-livepeer/actions/runs/14384181138/job/40335296309?pr=3389

I fixed the issue specific to this PR. Looks like the runners are having other issues now tho.

[ad-astra-video]

After re-running a few times all actions are now passing.