Update dotcom deployment configuration to consume GSM secrets - env vars only

Created by: ElizabethStirling

Consume the secrets we just added to the secret manager. Consume the secrets we just added to the secret manager. We should inject the secrets into the k8s deployment as k8s secrets through a CD step, or through GitHub Actions. K8s env vars should be pulled from these secrets.

Dependencies #17804 (closed)

Useful Links: GitHub action GSM k8s env var from secret

Repository: deploy-sourcegraph-dot-com