Remove unsupoorted alignment in execution tests

[petermcneeleychromium]

Given our spec changes on alignment, an alignment of 1 is invalid.
Since this is an execution test we should simply remove these cases.

If needed we can add additional validation test cases
(eg in webgpu/shader/validation/shader_io/align.spec.ts)

crbug.com/375467276

For reference the error generated when compiling is:

EXCEPTION: Error: Unexpected validation error occurred: Error while parsing WGSL: :7:10 error: alignment must be a multiple of '4' bytes for the 'storage' address space
@align(1) member_0 : i32,
^

:3:23 note: 'MyStruct' used in address space 'storage' here
@group(0) @binding(1) var<storage> input : MyStruct;