uni01alpha - Remove NeutronDhcpAgent on networkers

The RHOSO uni01alpha architecture does not enable NeutronDhcpAgent on
the networker nodes. Align the OSP17.1 Networkers to match.

Jira: OSPRH-15749

Author: hjensas

scenarios/uni01alpha/roles.yaml

@@ -279,7 +279,6 @@
     - OS::TripleO::Services::LoginDefs
     - OS::TripleO::Services::MetricsQdr
     - OS::TripleO::Services::MySQLClient
-    - OS::TripleO::Services::NeutronDhcpAgent
     - OS::TripleO::Services::NeutronL2gwAgent
     - OS::TripleO::Services::NeutronL3Agent
     - OS::TripleO::Services::NeutronMetadataAgent