Update helm values file to move controller.serviceMonitor to prometheus.serviceMonitor

[shaun-nx]

Proposed changes

This PR moves the ServiceMonitor fields from controller.serviceMonitor to prometheus.serviceMonitor in the helm values files.
This is being done to bring the creation of ServiceMonitor closer to where the Prometheus Service itself is created.

Helm command used to deploy:

~/deployments/helm-chart » helm install prometheus \
--set controller.kind=deployment \
--set controller.nginxplus=true \
--set controller.image.repository=nginx-plus-ingress \
--set controller.image.tag="moveServiceMonitor" \
--set prometheus.service.create=true \
--set prometheus.serviceMonitor.create=true \
--set prometheus.serviceMonitor.labels.product="nic" \
--set controller.replicaCount=5 .

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov]

Codecov Report

Merging #4351 (aad352c) into main (372aeb9) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #4351   +/-   ##
=======================================
  Coverage   52.19%   52.19%           
=======================================
  Files          59       59           
  Lines       16929    16929           
=======================================
  Hits         8836     8836           
  Misses       7796     7796           
  Partials      297      297           

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[ADubhlaoich]

LGTM!