Do not scale HEIF images

For the devices with dispaly density smaller than the default density,
the image decoder takes the ratio and scales the size of the decoded
image; this would cause test failures. To avoid such cases, this change
updates below two test cases to decode given HEIF images without
scaling.

- testDecode10BitHeif
- testDecode10BitHeifWithLowRam

Bug: 358128075
Test: atest android.graphics.cts.ImageDecoderTest#testDecode10BitHeif
Flag: EXEMPT test fix only
(cherry picked from commit 1faedab405db03405e7f33245aae7c8c8d55bce4)
Change-Id: I614ba0735aee56e23d5be501b1d2b57ca8f4fb3a