[O11y][Stan] Stan Lens migration

[rajvi-patel-22]

Manually migrate Stan visualizations to the lens in the Kibana version ^8.0.0 itself.

Preparation of data for testing

• Use sample_event.json / setup live instance using docker / mock data using a mock server to populate dashboards

Migration stats

	Before Migration		After Migration
	Lens	Vizualization	Lens	Vizualization
[Metrics Stan] Channel Overview Metrics	0	2	2	0
[Logs STAN] Overview	0	9	8	1

Dashboard : [Metrics Stan] Channel Overview Metrics

• Migrate visualization to the lens.
  • [O11y][Stan] Migrate Logs Overview Dashboard Visualizations to Lens #8188

Dashboard : [Logs STAN] Overview

• Migrate visualization to the lens.
  • [O11y][Stan] Migrate Channel Overview Metrics Dashboard Visualizations to Lens #8190

Verification and Validation

• Verification of functionality remains the same after migration in Kibana
• Verification of data count of after-migrated visualization with before-migrated visualization in Kibana
• Verification of Dashboards is not distorted in the supported Kibana version ^8.0.0