Fix CODEOWNERS patterns for submodules (#8372)
Fix CODEOWNERS patterns for submodules (#8372)

Git considers these files, not directories. Note that matches happen on
an entire path segment, so codeowners would still be set for a
hypothetical third_party/tensorflow_foo submodule.
iree-org/iree,google/iree,google/iree,google/iree,google/iree,iree-org/iree,google/iree,iree-org/iree,iree-org/iree,iree-org/iree,google/iree,iree-org/iree,google/iree,iree-org/iree