CODEOWNERS: Remove obsolete entries

These removed entries refer to paths that have already been deleted in
earlier commits. They no longer serve any purpose.

CODEOWNERS

@@ -2,26 +2,17 @@
 # More on CODEOWNERS files: https://help.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners
 
 # Remote-state backend                  # Maintainer
-/internal/backend/remote-state/artifactory       Unmaintained
 /internal/backend/remote-state/azure             @hashicorp/terraform-azure
 /internal/backend/remote-state/consul            Unmaintained
 /internal/backend/remote-state/cos               @likexian
-/internal/backend/remote-state/etcdv2            Unmaintained
-/internal/backend/remote-state/etcdv3            Unmaintained
 /internal/backend/remote-state/gcs               @hashicorp/terraform-google @hashicorp/terraform-ecosystem-strategic
 /internal/backend/remote-state/http              @hashicorp/terraform-core
-/internal/backend/remote-state/manta             Unmaintained
 /internal/backend/remote-state/oss               @xiaozhu36
 /internal/backend/remote-state/pg                @remilapeyre
 /internal/backend/remote-state/s3                @hashicorp/terraform-aws
-/internal/backend/remote-state/swift             Unmaintained
 /internal/backend/remote-state/kubernetes        @jrhouston @alexsomesan
 
 # Provisioners
-builtin/provisioners/chef               Deprecated
 builtin/provisioners/file               @hashicorp/terraform-core
-builtin/provisioners/habitat            Deprecated
 builtin/provisioners/local-exec         @hashicorp/terraform-core
-builtin/provisioners/puppet             Deprecated
 builtin/provisioners/remote-exec        @hashicorp/terraform-core
-builtin/provisioners/salt-masterless    Deprecated