Prevent filament grinding leaves wrong extruder selected

[dstoutamire]

"Prevent Filament Grinding" is selected by default. It produces gcode with snippets like this:

;prevent filament grinding on T1
G1 F12000
T0
T1
G91
G1 F12000 Z2
G90
G1 F1200 E733.80271
G1 F189 E739.80271
G1 F2400 E733.80271
G4 P2000
G92 E727.80271
G1 F12000 X139.096 Y118.65
G91
G1 F12000 Z-2
G90
;end of the filament grinding prevention protocol

Note that this leaves T1 selected. The problem is that it is there even if T1 is not in the layer, so the wrong head gets used. For example, when we print only using T1 for an adhesion brim, T1 should never be selected after the first layer.

This can be reproduced with the default profiles with any sufficiently-tall model and selecting "Build Plate Extrusion Extruder" of "Extruder Right". De-selecting "Prevent Filament Grinding" fixes the problem.