Fix OPAL Client Metrics Failure

[psardana]

…l-server and opal-client images to specific versions for stability

1. change otel-collector port mapping from 8888 to 8889 to avoid conflicts
2. add otel-collector to Prometheus scrape configuration for monitoring
3. replace OpenTelemetry metrics with Prometheus Gauge for policy store status tracking and simplify metric update logic

Changes proposed

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