MB-52451 - "serverless" mode as an option for search service

The value of this option would be "default" in the on-premise
deployment model and "serverless" in elixir deployments.

Change-Id: I11a2a0490ee26cd50a993df432ba0ab5c4224fe9
Reviewed-on: https://review.couchbase.org/c/ns_server/+/175809
Reviewed-by: Abhinav Dangeti <[email protected]>
Reviewed-by: Bryan McCoid <[email protected]>
Well-Formed: Build Bot <[email protected]>
Tested-by: Abhinav Dangeti <[email protected]>

Author: Sreekanth Sivasankaran

src/ns_ports_setup.erl

@@ -524,6 +524,7 @@ goport_args(fts, Config, _Cmd, NodeUUID) ->
         "defaultMaxPartitionsPerPIndex=1024," ++
         "bleveMaxResultWindow=10000," ++
         "failoverAssignAllPrimaries=false," ++
+        "deploymentModel=" ++ config_profile:name() ++ "," ++
         "cbaudit=" ++ atom_to_list(cluster_compat_mode:is_enterprise()) ++
         "," ++
         "ftsMemoryQuota=" ++ integer_to_list(FTSMemoryQuota * 1024000) ++ "," ++