[O11y][AWS] Incorrect fields in AWS Metrics Overview dashboard

[rajvi-patel-22]

Description

[Metrics AWS] Overview dashboard contains incorrect fields due to which we are not able to migrate those panels. Previously this issue (#3703) was identified and AWS dashboards were updated but it seems like this dashboard was miss out. First, we will have to update these panels with correct field names and then and only we would be able to migrate this dashboard to lens.

E.g., For below panel
Incorrect field: aws.elb.metrics.Latency
Correct field: aws.elb.metrics.Latency.avg

Screenshot

Update below fields in [Metrics AWS] Overview dashboard

Old Field	New Field
aws.ec2.cpu.total.pct	host.cpu.usage
aws.elb.metrics.Latency	aws.elb.metrics.Latency.avg
aws.elb.metrics.UnHealthyHostCount	aws.elb.metrics.UnHealthyHostCount.max
aws.lambda.metrics.Invocations	aws.lambda.metrics.Invocations.avg
aws.ecs.metrics.CPUUtilization	aws.ecs.metrics.CPUUtilization.avg
aws.ecs.metrics.CPUReservation	aws.ecs.metrics.CPUReservation.avg

[rajvi-patel-22]

PR is approved and merged, hence closing this issue: #6353