Drop "Debug" from the Generic Sensor WPT flakiness expectations

According to FindIt this is also affecting release builds such as mac-rel.
See https://bugs.chromium.org/p/chromium/issues/detail?id=833215#c22 for
example.

TBR=reillyg, wanming.lin@intel.com

Bug: 731018
Change-Id: I2ede287e13d3c9a3e7ff934859e70194c0110ea1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1807304Reviewed-by: Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>
Cr-Commit-Position: refs/heads/master@{#697545}

third_party/blink/web_tests/TestExpectations

@@ -6204,10 +6204,10 @@ crbug.com/1003055 virtual/threaded/external/wpt/css/css-scroll-snap/scroll-targe
 
 # Sheriff 2019-09-12
 crbug.com/1003268 [ Win10 ] fast/harness/internals-observe-gc.html [ Failure ]
-crbug.com/731018 [ Mac10.13 Debug ] external/wpt/accelerometer/Accelerometer.https.html [ Pass Failure ]
-crbug.com/731018 [ Mac10.13 Debug ] external/wpt/gyroscope/Gyroscope.https.html [ Pass Failure ]
-crbug.com/731018 [ Mac10.13 Debug ] external/wpt/orientation-sensor/AbsoluteOrientationSensor.https.html [ Pass Failure ]
-crbug.com/731018 [ Mac10.13 Debug ] external/wpt/orientation-sensor/RelativeOrientationSensor.https.html [ Pass Failure ]
+crbug.com/731018 [ Mac10.13 ] external/wpt/accelerometer/Accelerometer.https.html [ Pass Failure ]
+crbug.com/731018 [ Mac10.13 ] external/wpt/gyroscope/Gyroscope.https.html [ Pass Failure ]
+crbug.com/731018 [ Mac10.13 ] external/wpt/orientation-sensor/AbsoluteOrientationSensor.https.html [ Pass Failure ]
+crbug.com/731018 [ Mac10.13 ] external/wpt/orientation-sensor/RelativeOrientationSensor.https.html [ Pass Failure ]
 
 # TODO (csmartdalton): Remove after Skia roll and rebaseline
 crbug.com/630695 css3/filters/effect-blur-hw.html [ Pass Failure ]