Eliminate use of alias field_mask package

[liggitt]

The "google.golang.org/genproto/protobuf/..." package tree just contains aliases to known protobuf types.

It looks like newer protoc-gen-go versions correctly reference the known types in google.golang.org/protobuf/types/known/ and most generated packages have been updated recently.

Only three packages in genproto still reference anything within this package tree:

git grep "google.golang.org/genproto/protobuf/"
googleapis/cloud/irm/v1alpha2/incidents_service.pb.go:  field_mask "google.golang.org/genproto/protobuf/field_mask"
googleapis/devtools/containeranalysis/v1alpha1/containeranalysis.pb.go: field_mask "google.golang.org/genproto/protobuf/field_mask"
googleapis/devtools/remoteworkers/v1test2/tasks.pb.go:  field_mask "google.golang.org/genproto/protobuf/field_mask"

Can those be regenerated with a newer protoc-gen-go to reference the canonical type?

Eliminating use of the google.golang.org/genproto/protobuf/field_mask package would simplify kubernetes/kubernetes#113366 and remove the need for a submodule for the google.golang.org/genproto/protobuf package

[liggitt]

cc @quartzmo

[liggitt]

we might also want to mark the protobuf packages which are just alias packages now as deprecated to prompt people to switch to the canonical packages

[quartzmo]

It looks like all three files can be deleted as obsolete, is that correct @codyoss ?