Keycloak(RH-SSO 7.6.2) pod cannot start with `MTA_KEYCLOAK_POSTGRESQL_SERVICE_HOST: bad substitution` message in MTA Operator 6.1.0

Issue

Keycloak(RH-SSO 7.6.2) pod cannot start with the following message:

% oc get pod
NAME                                       READY   STATUS    RESTARTS      AGE
keycloak-0                                 0/1     Running   3 (49s ago)   2m41s <<== CANNOT START
mta-keycloak-postgresql-84f6b65865-rdk4q   1/1     Running   0             15m
mta-operator-77b6c49d95-9vv8x              1/1     Running   0             17m
rhsso-operator-656589965c-gsdk7            1/1     Running   0             13s
% oc logs keycloak-0
..snip..
Added 'admin' to '/opt/eap/standalone/configuration/keycloak-add-user.json', restart server to load user
INFO Access log is disabled, ignoring configuration.
/opt/eap/bin/openshift-launch.sh: line 67: KEYCLOAK_POSTGRESQL_SERVICE_HOST
MTA_KEYCLOAK_POSTGRESQL_SERVICE_HOST: bad substitution  <<== HERE

So the Keycloak pod restart repeatedly.