As a pre-requisite to support DCAEGEN2-1972, PH pod needs to be enhanced to source the password from k8s secrets or environment variable. Following change is necessary for PH.

1. Source username, password as separate parameter and used that for Authorization in header. Currently "Authorization": "Basic aGVhbHRoY2hlY2s6emIhWHp0RzM0" is stored in directly on KV (from https://git.onap.org/oom/tree/kubernetes/dcaegen2/components/dcae-policy-handler/resources/config/config.json). The username/password (healthcheck/zb!XztG34) should be sourced as separate parameter and Authorization header constructed from it.
2. Source password from environment variable when available - this should take precedence over consul KV parameter. However if environment variable is not set, consul KV parameter should be used as currently done

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implementation:

policy-handler is enhanced to get user/password from env vars for PDP and DMaaP MR clients and overwriting the Authorization field in https headers received from the discoverable config

• to override the Authorization value on policy_engine, set the environment vars $PDP_USER and $PDP_PWD in policy-handler
  container
• to override the Authorization value on dmaap_mr if using https and user-password authentication, set the environment vars $DMAAP_MR_USER and $DMAAP_MR_PWD in policy-handler container