Expect Validation Error from Copy Operations

[kunalmohan]

For invalid CopyBufferToBuffer, spec says to generate validation error in the copy operation itself.
Whereas the cts expects the validation error to be reported on commandEncoder.finish()-

cts/src/webgpu/api/validation/copyBufferToBuffer.spec.ts

Lines 45 to 49 in af5392c

	commandEncoder.copyBufferToBuffer(srcBuffer, srcOffset, dstBuffer, dstOffset, copySize);
	this.expectValidationError(() => {
	commandEncoder.finish();
	}, !isSuccess);

[kunalmohan]

This is no longer expected.