This PR fixes a bug where sidecar services would be re-registered into Consul every ~30
seconds, caused by the parent service having its tags field set and the sidecar_service
tags unset. Nomad would directly compare the tags between its copy of the sidecar service
definition and the tags of the sidecar service reported by Consul. This does not work,
because Consul will under-the-hood set the sidecar service tags to inherit the parent
service tags if the sidecar service tags are unset. The comparison then done by Nomad
would not match, if the parent sidecar tags are set.

Fixes #10025