Revert "test: ChromiteUnitTest also logs stderr"

This reverts commit 9dfbe164a6b2fac7bd9d992dbaf3aeb1540166cd.

Reason for revert: Does not solve what it was supposed to.

Original change's description:
> test: ChromiteUnitTest also logs stderr
> 
> TEST=run_tests
> BUG=chromium:972712
> 
> Change-Id: I7fbcd4880a640ac0c4a2e4a88121f2cec0df80f7
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1653601
> Tested-by: Evan Hernandez <evanhernandez@chromium.org>
> Reviewed-by: Jason Clinton <jclinton@chromium.org>
> Commit-Queue: Evan Hernandez <evanhernandez@chromium.org>

Bug: chromium:972712
Change-Id: I792b9cbee5ff2c2cc38c613be99c06536da821c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1670915
Reviewed-by: Evan Hernandez <evanhernandez@chromium.org>
Commit-Queue: Evan Hernandez <evanhernandez@chromium.org>
Tested-by: Evan Hernandez <evanhernandez@chromium.org>
diff --git a/api/controller/test.py b/api/controller/test.py
index 7df4f71..ddd09f2 100644
--- a/api/controller/test.py
+++ b/api/controller/test.py
@@ -96,8 +96,7 @@
 def ChromiteUnitTest(_input_proto, _output_proto):
   """Run the chromite unit tests."""
   cmd = [os.path.join(constants.CHROMITE_DIR, 'scripts', 'run_tests')]
-  result = cros_build_lib.RunCommand(cmd, error_code_ok=True,
-                                     combine_stdout_stderr=True)
+  result = cros_build_lib.RunCommand(cmd, error_code_ok=True)
   if result.returncode == 0:
     return controller.RETURN_CODE_SUCCESS
   else: