Remove support for typo in gcs secret

Overview

In https://gitlab.com/gitlab-org/charts/gitlab-runner/-/blob/5d15e6fba0f1f2a6f768745af3e521b71948fd30/templates/configmap.yaml#L23-24 we only register the CredentialsFile when there is a typo in the secret gcs-applicaton-credentials-file notice the missing i in application. This causes a lot of confusion for users as shown in #99 (closed).

To fix this issue without a breaking change we implemented !214 (merged) which adds an extra check for the correct name.

Proposal

1. Remove the extra check for the incorrect secret name https://gitlab.com/gitlab-org/charts/gitlab-runner/-/blob/39e79516e1e99a832c8857fe91b867d4c78b1241/templates/configmap.yaml#L23-24
2. Only support /secrets/gcs-application-credentials-file