tests: Update IgnoreUnrelatedDescriptor to use optimal tiling

Some android devices do not support linear for the requested format.
Changing to VK_IMAGE_TILING_OPTIMAL to allow such devices to pass this
test.
diff --git a/tests/layer_validation_tests.cpp b/tests/layer_validation_tests.cpp
index 99480c2..030e578 100644
--- a/tests/layer_validation_tests.cpp
+++ b/tests/layer_validation_tests.cpp
@@ -1065,7 +1065,7 @@
         image_create_info.mipLevels = 1;
         image_create_info.arrayLayers = 1;
         image_create_info.samples = VK_SAMPLE_COUNT_1_BIT;
-        image_create_info.tiling = VK_IMAGE_TILING_LINEAR;
+        image_create_info.tiling = VK_IMAGE_TILING_OPTIMAL;
         image_create_info.usage = VK_IMAGE_USAGE_SAMPLED_BIT;
         image_create_info.flags = 0;
         VkResult err =