Which chart:
I'm using rabbitmq-8.0.2.tar, which is specified as a requirement of OWASP DefectDojo Helm chart (https://github.com/DefectDojo/django-DefectDojo/blob/master/helm/defectdojo/requirements.yaml).

Describe the bug
I was previously using rabbit-6.18.2.tar and was able to set a value in the parent chart (DefectDojo) to override the security Context being set in the rabbitmq sub-chart. I could set securityContext.enabled=false in the parent chart and thus not use fsGroup: 1001 nor runAsUser: 1001 when deploying the chart:

securityContext:
  enabled: false
  fsGroup: 1001
  runAsUser: 1001
  extra: {}

This allows me to deploy in OpenShift, using the restricted SCC which automatically assigns an arbitrary (and non-root) UID to the container.

Since trying the deployment with 8.0.2 (and I've checked this still applies to the latest rabbit chart (8.6.1)) I cannot override this setting from the parent chart, as the rabbit values.yaml has been updated to:

podSecurityContext:
  fsGroup: 1001
  runAsUser: 1001

To Reproduce
Steps to reproduce the behavior:

1. Deploy chart to OpenShift, using a serviceAccount that is only permitted to use the restricted SCC
2. View the stateful set: oc describe sts <name> and see following event:

create Pod defect-dojo-rabbitmq-0 in StatefulSet defect-dojo-rabbitmq failed error: pods "defect-dojo-rabbitmq-0" is forbidden: unable to validate against any security context constraint: [fsGroup: Invalid value: []int64{1001}: 1001 is not an allowed group spec.containers[0].securityContext.securityContext.runAsUser: Invalid value: 1001: must be in the ranges: [1000640000, 1000649999]]

Expected behavior
I expect to be able to enable/disable the securityContext of rabbitmq both within rabbitMQ chart, and parent chart.

Version of Helm and Kubernetes:

• Output of helm version:

version.BuildInfo{Version:"v3.4.0", GitCommit:"7090a89efc8a18f3d8178bf47d2462450349a004", GitTreeState:"clean", GoVersion:"go1.14.10"}

• Output of kubectl version:

Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.4", GitCommit:"d360454c9bcd1634cf4cc52d1867af5491dc9c5f", GitTreeState:"clean", BuildDate:"2020-11-11T13:17:17Z", GoVersion:"go1.15.2", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"18+", GitVersion:"v1.18.3+ac53d20", GitCommit:"ac53d20", GitTreeState:"clean", BuildDate:"2020-10-31T17:54:45Z", GoVersion:"go1.13.4", Compiler:"gc", Platform:"linux/amd64"}

• Output of oc version:

oc v3.11.0+0cbc58b
kubernetes v1.11.0+d4cacc0
features: Basic-Auth GSSAPI Kerberos SPNEGO

Server
kubernetes v1.18.3+ac53d20