DO NOT MERGE: Update unsupportedDensity multiplication factor to 6

ag/9537749 allowed ARC application to support changes to zoom.
This CL updates the unspported density factor to be 6, as the
range of supported density values is in the range 0.25 to 5.0.
This range is defined in DPI_SCALE_FACTORS in TaskRecordArc.java.

Bug: b/143782981
Test: atest CtsActivityManagerDeviceTestCases:DisplaySizeTest#testCompatibilityDialog
Change-Id: I6294573e18fb9292a38f13e2b74bafd434f7e8e3