cheets_CTS/GTS/STS: (experiment) Unconditionally keep screen on.

The previous blocker (b/137228533) was on ARC-N boards and
several workarounds were added for it since then. Let's try
reenabling it for all the tests, instead of special-casing
a few more emerging tests that needs screen kept on.

BUG=b:179981564
TEST=cheets_CTS_Instant.9.0_r14.x86.all.CtsBackgroundRestrictions\
  TestCases_-_CtsPrintTestCases

Change-Id: I2d9723f1161485a67fc66eefd0933e8a5782ab64
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2691591
Tested-by: Kazuhiro Inaba <kinaba@chromium.org>
Auto-Submit: Kazuhiro Inaba <kinaba@chromium.org>
Commit-Queue: Shao-Chuan Lee <shaochuan@chromium.org>
Reviewed-by: Shao-Chuan Lee <shaochuan@chromium.org>
diff --git a/server/cros/tradefed/tradefed_test.py b/server/cros/tradefed/tradefed_test.py
index fa1ed2e..a896a4e 100644
--- a/server/cros/tradefed/tradefed_test.py
+++ b/server/cros/tradefed/tradefed_test.py
@@ -1320,17 +1320,12 @@
                     # enough disk space for 16GB storage devices: b/156075084.
                     if not keep_media:
                         self._clean_crash_logs()
-                # TODO(b/137917339): Only prevent screen from turning off for
-                # media tests. Remove this check once the GPU issue is fixed.
-                keep_screen_on = (media_asset and media_asset.uri) or (
-                        target_module and "Media" in target_module)
-                if keep_screen_on:
-                    self._override_powerd_prefs()
+                # Prevent screen from turning off
+                self._override_powerd_prefs()
                 try:
                     waived_tests, acc = self._run_and_parse_tradefed(command)
                 finally:
-                    if keep_screen_on:
-                        self._restore_powerd_prefs()
+                    self._restore_powerd_prefs()
                 if media_asset:
                     self._fail_on_unexpected_media_download(media_asset)
                 result = self._run_tradefed_list_results()