treewide: use a single append to concatenate two slices

Change-Id: I3930313203c753aa5e629af0db3bf604baaa6b43
Reviewed-on: https://review.monogon.dev/c/monogon/+/3011
Reviewed-by: Serge Bazanski <serge@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/node/build/fsspec/utils.go b/metropolis/node/build/fsspec/utils.go
index c51df06..f5a45e3 100644
--- a/metropolis/node/build/fsspec/utils.go
+++ b/metropolis/node/build/fsspec/utils.go
@@ -21,18 +21,10 @@
 		if err := prototext.Unmarshal(specRaw, &spec); err != nil {
 			return nil, fmt.Errorf("failed to parse spec %q: %w", p, err)
 		}
-		for _, f := range spec.File {
-			mergedSpec.File = append(mergedSpec.File, f)
-		}
-		for _, d := range spec.Directory {
-			mergedSpec.Directory = append(mergedSpec.Directory, d)
-		}
-		for _, s := range spec.SymbolicLink {
-			mergedSpec.SymbolicLink = append(mergedSpec.SymbolicLink, s)
-		}
-		for _, s := range spec.SpecialFile {
-			mergedSpec.SpecialFile = append(mergedSpec.SpecialFile, s)
-		}
+		mergedSpec.File = append(mergedSpec.File, spec.File...)
+		mergedSpec.Directory = append(mergedSpec.Directory, spec.Directory...)
+		mergedSpec.SymbolicLink = append(mergedSpec.SymbolicLink, spec.SymbolicLink...)
+		mergedSpec.SpecialFile = append(mergedSpec.SpecialFile, spec.SpecialFile...)
 	}
 	return &mergedSpec, nil
 }
diff --git a/metropolis/node/core/mgmt/svc_logs_test.go b/metropolis/node/core/mgmt/svc_logs_test.go
index 734a149..fea8068 100644
--- a/metropolis/node/core/mgmt/svc_logs_test.go
+++ b/metropolis/node/core/mgmt/svc_logs_test.go
@@ -101,9 +101,7 @@
 			t.Errorf("Recv: %v", err)
 			return
 		}
-		for _, e := range ev.BacklogEntries {
-			res = append(res, e)
-		}
+		res = append(res, ev.BacklogEntries...)
 	}
 }
 
diff --git a/metropolis/pkg/logtree/logtree_test.go b/metropolis/pkg/logtree/logtree_test.go
index e37893a..54eabb7 100644
--- a/metropolis/pkg/logtree/logtree_test.go
+++ b/metropolis/pkg/logtree/logtree_test.go
@@ -66,9 +66,7 @@
 
 	var lines []string
 	for _, e := range res.Backlog {
-		for _, msg := range e.Leveled.Messages() {
-			lines = append(lines, msg)
-		}
+		lines = append(lines, e.Leveled.Messages()...)
 	}
 	return lines
 }