Adding request path tag for Istio request metric

Problem Statement Istio collects metrics by default in prometheus format. Request metrics that are collected by default have annotations (or tags) like response_code, destination_service etc however information about url_path is not present.

Change Details This MR adds the custom tags - request_method and 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.