refactor: add AI service registry info log line

[rickstaa]

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

This pull request logs when the AI ServiceRegistry is used instead of the regular registry.

Specific updates (required)

• Added one log line in starter.go.

How did you test each of these updates (required)

Run the binary.

Does this pull request close any open issues?

No.

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

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 33.69559%. Comparing base (56ab75e) to head (57250f1).

Files with missing lines	Patch %	Lines
cmd/livepeer/starter/starter.go	0.00000%	1 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3362         +/-   ##
===================================================
- Coverage   33.70183%   33.69559%   -0.00624%     
===================================================
  Files            141         141                 
  Lines          37449       37450          +1     
===================================================
- Hits           12621       12619          -2     
- Misses         24107       24110          +3     
  Partials         721         721                 

Files with missing lines	Coverage Δ
cmd/livepeer/starter/starter.go	7.50939% <0.00000%> (-0.00470%)	⬇️

... and 2 files with indirect coverage changes

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Files with missing lines	Coverage Δ
cmd/livepeer/starter/starter.go	7.50939% <0.00000%> (-0.00470%)	⬇️

... and 2 files with indirect coverage changes