blobstore: Use discoverd for deployments
blobstore: Use discoverd for deployments

If the blobstore starts but then fails to validate the S3 config, the
deploy should fail, and using discoverd rather than job events
accomplishes that.

Signed-off-by: Lewis Marshall <748e1641a368164906d4a0c0e3965345453dcc93@lmars.net>

lmars/flynn,philiplb/flynn,philiplb/flynn,flynn/flynn,lmars/flynn,lmars/flynn,flynn/flynn,philiplb/flynn,flynn/flynn,philiplb/flynn,lmars/flynn,lmars/flynn,flynn/flynn,flynn/flynn,philiplb/flynn