fix(ci): remove xvfb-action from self-hosted runner #743

Job	Run time
Moonshine STT Check (Optional)	19s
Security Audit	14s
Validate Workflow Definitions	5s
Setup Whisper Dependencies	5s
Unit Tests & Golden Master (Hosted) (stable)	6m 3s
Hardware Integration Tests (Self-Hosted)	2m 50s
CI Success Summary	5s
	9m 41s

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