tint: remove LoopToForLoop and FoldTrivialSingleUseLets transforms for HLSL and GLSL

Change-Id: I18c807b2449dc2842cb9dbfaeba98dae640d2355
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/102621
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>

test/tint/expressions/binary/mod/vec3-scalar/u32.wgsl.expected.glsl

@@ -2,7 +2,8 @@
 
 void f() {
   uvec3 a = uvec3(1u, 2u, 3u);
-  uvec3 r = (a % 4u);
+  uint b = 4u;
+  uvec3 r = (a % b);
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;