Add a Gauge method for recording event metrics

[yosrixp]

Description

Implemented an optimized metric registration: OpenTelemetryMetric now caches CounterBuilder instances in a concurrent map,

• Registering each metric name only once instead of creating a new builder on every increment.
• Added a gauge(name, domain, service, value) method to record event metrics at scrape time.

Contribution Checklist:

• The pull request does not introduce any breaking changes
• I have read the contribution guidelines.
• Create an issue and link to the pull request.

Attach Screenshots (Optional)