Update input color in YUVSampleLinearFiltering test

This test uses narrow range encoding (as can be seen from the
color value for black) but the Cr component for red is greater
than 240. On some platforms with different clamping logic the
output color after conversion ends up not being red. Update the
input colors to account for different implementations.

Bug: b/210526871
Test: ImageTestES3.SourceYUVAHBTargetExternalYUVSampleLinearFiltering*
Change-Id: Ib9b76c9433b07f5ce8a129779e77bc682bb341ac
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4684018
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>

src/tests/gl_tests/ImageTest.cpp

@@ -3222,17 +3222,17 @@ TEST_P(ImageTestES3, SourceYUVAHBTargetExternalYUVSampleLinearFiltering)
 
     // clang-format off
     GLubyte dataY[]  = {
-        76, 76,
-        76, 76,
+        81, 81,
+        81, 81,
         16, 16,
         16, 16,
     };
     GLubyte dataCb[] = {
-        84,
+        90,
         128,
     };
     GLubyte dataCr[] = {
-        255,
+        240,
         128,
     };
     // clang-format on