Fix bug in repair

[raymondjacobson]

Seeing large number of these logs on creatornode.audius.co

audiusd-0 audiusd 1.7683583622940142e+09	error	exist check failed	{"node": "https://creatornode.audius.co", "service": "mediorum", "task": "repair", "cid": "baeaaaiqsedrfda77f4tr6drkjh53ecwhfbspd2fl5fs6fsltsjwtix4i5omk6", "cleanup": true, "error": "blob (key \"5omk6/baeaaaiqsedrfda77f4tr6drkjh53ecwhfbspd2fl5fs6fsltsjwtix4i5omk6\") (code=Unknown): storage: object doesn't exist: googleapi: Error 404: No such object: creator-1/5omk6/baeaaaiqsedrfda77f4tr6drkjh53ecwhfbspd2fl5fs6fsltsjwtix4i5omk6, notFound", "errorVerbose": "blob (key \"5omk6/baeaaaiqsedrfda77f4tr6drkjh53ecwhfbspd2fl5fs6fsltsjwtix4i5omk6\") (code=Unknown):\n    gocloud.dev/blob.(*Bucket).Attributes\n        /home/runner/go/pkg/mod/gocloud.dev@v0.40.0/blob/blob.go:919\n  - storage: object doesn't exist: googleapi: Error 404: No such object: creator-1/5omk6/baeaaaiqsedrfda77f4tr6drkjh53ecwhfbspd2fl5fs6fsltsjwtix4i5omk6, notFound"}

which means the gcerrors.Code(err) == gcerrors.NotFound is insufficient with gcs at least, or at least partially. continue repair in that case.

this hasn't changed in ages, so not sure why this is happening!