fix: satisfy golangci-lint on the Linux-only detachedCommand test

Remove an unused helper left over from an earlier edit and reformat a call
site golines flagged. The Linux build tag meant a local darwin lint run
never analyzed this file; only GOOS=linux (as CI's ubuntu-latest job runs
natively) caught it.

Author: mlataza

cmd/agent_smith/run_command_linux_test.go

@@ -9,7 +9,12 @@ import (
 )
 
 func TestDetachedCommandWrapsInSystemdScope(t *testing.T) {
-	cmd := detachedCommand("/opt/agent/rewst_agent_config.linux.bin", []string{"--update", "--org-id", "abc"}, os.Stdout, os.Stderr)
+	cmd := detachedCommand(
+		"/opt/agent/rewst_agent_config.linux.bin",
+		[]string{"--update", "--org-id", "abc"},
+		os.Stdout,
+		os.Stderr,
+	)
 
 	wantPath := "systemd-run"
 	if got := cmd.Path; got != wantPath && !strings.HasSuffix(got, "/"+wantPath) {
@@ -43,7 +48,3 @@ func TestDetachedCommandWrapsInSystemdScope(t *testing.T) {
 		t.Fatalf("Setsid = false, want true")
 	}
 }
-
-func endsWith(s, suffix string) bool {
-	return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix
-}