Upgrading GitLab Runner operator to 1.25 fails with OwnNamespace InstallModeType not supported

We are using Gitlab.com with the Gitlab Runner on OpenShift 4, installed to a "specific namespace". While upgrading the Gitlab Runner Operator to 1.25.0 the operator fails with "OwnNamespace InstallModeType not supported, cannot configure to watch own namespace".

This is problematic because it coincides with the new runner registration workflow so previous version can also not start any runners.

It seems that the OwnNamespace is no longer supported while previously it was:

oc describe csv gitlab-runner-operator.v1.25.0
...  
  Install Modes:
    Supported:  false
    Type:       OwnNamespace
    Supported:  false
    Type:       SingleNamespace
    Supported:  false
    Type:       MultiNamespace
    Supported:  true
    Type:       AllNamespaces
...

Reinstalling the operator does not support installation to a specific namespace:

Previously it seems this was possible as suggested by the documentation at https://docs.gitlab.com/runner/install/operator.html.

Note: Extracted this from #208 (comment 1948903993), while related, it seems to be a different problem.