When using a Perses datasource pointing to in-cluster services. The CA seems not to be included and the perses proxy client cannot verify the target service.

Steps to reproduce:

1. Install COO with OpenShift enabled
2. Install the monitoring UI plugin with the perses feature enabled
3. Wait until the monitoring plugin deployment and perses backend stateful set are created
4. Create a peses-dev namespace in which the Perses datasource and dashboard will be created
5. Create a Datasource connecting to in cluster thanos querier: https://github.com/perses/perses-operator/blob/main/config/samples/openshift/thanos-querier-datasource.yaml 
6. Create a Dashboard that consumes this datasource: https://github.com/perses/perses-operator/blob/main/config/samples/openshift/openshift-cluster-sample-dashboard.yaml 
7. Navigate in the console to Observe -> Perses Dashboards
8. The dashboard shows an unauthorized error

Expected behavior

• Dashboards load data from the Thanos querier without issues
• Changing the time range fetches new data without issues