Adding request path tag for Istio request metric
Istio collects metrics by default in prometheus format. Request metrics that are collected by default have annotations (or tags) like
destination_service etc however information about url_path is not present.
This MR adds the custom tags -
request_url_path to request metrics. The metric tags are added in operator.yaml file - this add the tags at mesh level and we do not need any extra configuration at pod level.