Add carrier as hostlabels to migrate cellular tests

Add DUT carrier to hostlabels so it can be used in cellular tests while
they're migrated to TFC. For TFC tests this information is passed
directly via the Cellular.Carrier field in the DUT proto.

BUG=b:333911546
TEST=~/trunk/src/platform/dev/fast_build.sh -T

Change-Id: I6f923029ba9d369df1a2b152508c0fed824b982f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/5455103
Commit-Queue: Jason Stanko <[email protected]>
Reviewed-by: Derek Beckett <[email protected]>
Tested-by: Jason Stanko <[email protected]>
2 files changed