Add newline to each generated bash script in rbe_test.go.

"exec format error" showed up on Mac when running the rbe_test.go.
The generated bash scripts did not have a newline at the end of
the file.

Bug: b/162600461
Fixes: b/162600461

Test: "m blueprint_tools" on Android Mac builder.
Change-Id: I425fa5f428733b6569c3fcdaa312023f9761d020
Merged-In: I425fa5f428733b6569c3fcdaa312023f9761d020

ui/build/rbe_test.go

@@ -105,12 +105,12 @@ func TestDumpRBEMetricsErrors(t *testing.T) {
 	}, {
 		description:         "stopRBE failed",
 		rbeOutputDirDefined: true,
-		bootstrapProgram:    "#!/bin/bash\nexit 1",
+		bootstrapProgram:    "#!/bin/bash\nexit 1\n",
 		expectedErr:         "shutdown failed",
 	}, {
 		description:         "failed to copy metrics file",
 		rbeOutputDirDefined: true,
-		bootstrapProgram:    "#!/bin/bash",
+		bootstrapProgram:    "#!/bin/bash\n",
 		expectedErr:         "failed to copy",
 	}}
 
@@ -159,4 +159,4 @@ func TestDumpRBEMetricsErrors(t *testing.T) {
 	}
 }
 
-var rbeBootstrapProgram = fmt.Sprintf("#!/bin/bash\necho 1 > $RBE_output_dir/%s", rbeMetricsPBFilename)
+var rbeBootstrapProgram = fmt.Sprintf("#!/bin/bash\necho 1 > $RBE_output_dir/%s\n", rbeMetricsPBFilename)