Use wide gamut color mode for blur test activities

The tests check that exact colors are drawn on the screen. Device
color mode should not interfere with the colors. Making the colorMode
wideColorGamut prevents color stretching, which distorts final colors
on the screenshots and causes the tests to fail

Bug: 193861404
Test: atest BlurTests
Change-Id: Idceb0fdd2f6b539f00f00625d0d1155b57a8d875
1 file changed