Security context changes

[abimichel]

Security context changes are:

1. Set the PodSecurityContexts and ContainerSecurityContexts to be OpenShift compatible – using the values.yaml.
2. Created namespace policies that assign unlabeled pods with a DataClass=Medium label.
3. Created ingress/egress network policies for OpenMetadata and all dependencies (Airflow, OpenSearch, MySQL).

Steps I followed are documented here: (https://apps.nrs.gov.bc.ca/int/confluence/x/jYQlCw)
under "Checklist to set up a Helm deployment for OpenShift Emerald Cluster"

Other minor changes:

• Lowered resource requests
• Extended timeout of startup probe from 1 second to 10
• Simplified the custom Dockerfile for OpenSearch. Automated to publish to GHCR.
• Updated to chart version 1.2.8

To review all Helm chart modifications (i.e. differences between the OpenMetadata default config and this config), search this branch for "DF-NOTE:" annotations.