Switch FW test to use new Webplot module

This switched the FW test to use the new-style Webplot module.
After Joseph's rework, I was able to completely eliminate the
TouchPlotter class, which results in a lot clearer code as well
as much more reuse between webplot and touch_firmware_test.

I had to alter a few things about Webplot, such as removing the
RemoteTouchDeviceWrapper class, but it didn't really do much
anyway, and I believe the rest of the module works just fine with
my minor modifications.

BUG=chromium:474709
TEST=manual testing and everything looked okay from what I could tell.

Change-Id: Ib7f4aa854fcda0c67b5627f20b2054df08cabad5
Signed-off-by: Charlie Mooney <charliemooney@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/266081
diff --git a/gesture_interpreter.py b/gesture_interpreter.py
index d7b6cf1..be2bf41 100644
--- a/gesture_interpreter.py
+++ b/gesture_interpreter.py
@@ -50,4 +50,4 @@
 
 def _PerformStationaryNoiseTest(variation, robot, device_spec):
   frequency, amplitude, waveform, location = variation
-  robot.Tap(device_spec, LOCATION_COORDINATES[location], touch_time_s=5)
+  robot.Tap(device_spec, LOCATION_COORDINATES[location], touch_time_s=4)