Modify Container Registry Helm chart to allow Deployment and other objects to be disabled

Problem statement

Post deployment migrations (PDMs) for the Container Registry metadata database on production, staging and preprod are currently executed manually. In this epic (gitlab-org&17933 (closed)), we are automating the execution of PDMs of Container Registry.

Since we're using the same Helm chart for deploying Container Registry application and for executing migrations, we need to disable other objects when executing migrations. For example, the Deployment object is not required when we only want to execute migrations.

Proposal

Create a Helm value like runMigrations=true in the Container Registry chart that disables all objects that are not required for executing migrations.

Implemented

An registry.api.enabled value was added. Resources in the registry chart, that are not required for executing migrations can be disabled with this value.