[Internal] Open Telemetry: Fixes Metric Name and Unit changes

[sourabh1007]

Description

Changes in Metric and Unit Names

Metric Name (Old)	Metric Name (New)	Otel Official Link
db.client.response.row_count	db.client.response.returned_rows	https://opentelemetry.io/docs/specs/semconv/database/cosmosdb/#metric-dbclientresponsereturned_rows

Metric Name	Old Unit	New Unit	Otel Official Link
db.client.response.returned_rows	#	{item}	https://opentelemetry.io/docs/specs/semconv/database/database-metrics/#metric-dbclientresponsereturned_rows
azure.cosmosdb.client.active_instance.count	#	{instance}	https://opentelemetry.io/docs/specs/semconv/database/cosmosdb/#metric-azurecosmosdbclientactive_instancecount
db.client.response.request_unit	# RU	{request_unit}	https://opentelemetry.io/docs/specs/semconv/database/cosmosdb/#metric-azurecosmosdbclientoperationrequest_charge

Since, this feature is under preview, Hence, not following versioning for this.

Type of change

• [] Bug fix (non-breaking change which fixes an issue)

Closing issues

To automatically close an issue: closes #5066

[kundadebdatta]

LGTM