Backport of add a conditional around setting LANFilter.AllSegments to make sure it is valid into release/1.16.x (#18146)

* no-op commit due to failed cherry-picking

* add a conditional around setting LANFilter.AllSegments to make sure it is valid (#18139)

This is to correct a code problem because this assumes all segments, but
when you get to Enterprise, you can be in partition that is not the
default partition, in which case specifying all segments does not
validate and fails. This is to correct the setting of this filter with
`AllSegments` to `true` to only occur when in the the `default`
partition.

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* [ ] updated test coverage
* [ ] external facing docs updated
* [ ] appropriate backport labels added
* [ ] not a security concern

---------

Co-authored-by: temp <temp@hashicorp.com>
Co-authored-by: John Murret <john.murret@hashicorp.com>

agent/ui_endpoint.go

@@ -190,7 +190,11 @@ func AgentMembersMapAddrVer(s *HTTPHandlers, req *http.Request) (map[string]stri
 	filter := consul.LANMemberFilter{
 		Partition: entMeta.PartitionOrDefault(),
 	}
-	filter.AllSegments = true
+
+	if acl.IsDefaultPartition(filter.Partition) {
+		filter.AllSegments = true
+	}
+
 	lanMembers, err := s.agent.delegate.LANMembers(filter)
 	if err != nil {
 		return nil, err