Remove gitlab.kas.privateApi.tls.enabled and gitlab.kas.privateApi.tls.secretName
Summary
These were deprecated long ago: Add deprecation note to GitLab deprecations reg... (#4097 - closed).
We should remove support for these configs.
As per Improve KAS TLS UX (!2888 - merged), we should use global.kas.tls.enabled
and global.kas.tls.secretName
instead.