Remove copying Merge() on Report

It was only used in a few places, and all of those were better off
using the Unsafe variant.

app/collector_test.go

@@ -50,8 +50,8 @@ func TestCollector(t *testing.T) {
 
 	c.Add(ctx, r2, nil)
 	merged := report.MakeReport()
-	merged = merged.Merge(r1)
-	merged = merged.Merge(r2)
+	merged.UnsafeMerge(r1)
+	merged.UnsafeMerge(r2)
 	have, err = c.Report(ctx, mtime.Now())
 	if err != nil {
 		t.Error(err)

probe/plugins/registry.go

@@ -222,7 +222,7 @@ func (r *Registry) Report() (report.Report, error) {
 		if plugin.Implements("controller") {
 			r.updateAndRegisterControlsInReport(&pluginReport)
 		}
-		rpt = rpt.Merge(pluginReport)
+		rpt.UnsafeMerge(pluginReport)
 	})
 	return rpt, nil
 }

render/theinternet_test.go

@@ -10,7 +10,7 @@ import (
 )
 
 func TestReportLocalNetworks(t *testing.T) {
-	r := report.MakeReport().Merge(report.Report{
+	r := report.Report{
 		Host: report.Topology{
 			Nodes: report.Nodes{
 				"nonets": report.MakeNode("nonets"),
@@ -27,7 +27,7 @@ func TestReportLocalNetworks(t *testing.T) {
 				),
 			},
 		},
-	})
+	}.Copy()
 	want := report.MakeNetworks()
 	for _, cidr := range []string{"10.0.0.1/8", "192.168.1.1/24", "10.32.0.1/12"} {
 		if err := want.AddCIDR(cidr); err != nil {

report/report.go

@@ -334,14 +334,6 @@ func (r Report) Copy() Report {
 	return newReport
 }
 
-// Merge merges another Report into the receiver and returns the result. The
-// original is not modified.
-func (r Report) Merge(other Report) Report {
-	newReport := r.Copy()
-	newReport.UnsafeMerge(other)
-	return newReport
-}
-
 // UnsafeMerge merges another Report into the receiver. The original is modified.
 func (r *Report) UnsafeMerge(other Report) {
 	r.DNS = r.DNS.Merge(other.DNS)