Fix textureLoad test for multisampled textures

Multisampled textures are required to have RENDER_ATTACHMENT usage.
This was working by accident as `createTextureWithRandopmDataAndGetTexels`
as adding the RENDER_ATTACHMENT usage. That usage addition is removed
in this PR so the bug that it was not added here surfaced.

Author: greggman

src/webgpu/shader/execution/expression/call/builtin/textureLoad.spec.ts

@@ -369,7 +369,10 @@ Parameters:
     const descriptor: GPUTextureDescriptor = {
       format,
       size: [8, 8],
-      usage: GPUTextureUsage.COPY_DST | GPUTextureUsage.TEXTURE_BINDING,
+      usage:
+        GPUTextureUsage.COPY_DST |
+        GPUTextureUsage.TEXTURE_BINDING |
+        GPUTextureUsage.RENDER_ATTACHMENT,
       sampleCount,
     };
     const { texels, texture } = await createTextureWithRandomDataAndGetTexels(t, descriptor);