jmx_prometheus_javaagent jar needed into IAM docker image

[federicaagostini]

CERN team needs the jmx_prometheus_javaagent jar to collect IAM metrics. Right now, they just create a new image from IAM such as

ARG IAM_BASE_IMAGE
ARG IAM_BASE_TAG
FROM $IAM_BASE_IMAGE:$IAM_BASE_TAG
COPY jmx_prometheus_javaagent-0.20.0.jar /tmp/

The request is to install the package directly on the IAM docker image.