Some macros are redundant or unused.
- WASM_RETURN1 is identical to WASM_RETURN.
- WASM_RETURNN has an unused {count} parameter, and is otherwise
  identical to WASM_RETURN.
- WASM_IFB is identical to WASM_IF.
- WASM_CASE and WASM_CASE_BR are unused.
- WASM_BR_TABLEV is unused.

R=thibaudm@chromium.org

Bug: v8:12244
Change-Id: Ie7be00351f2dfe38d6e84d80e157a85df37233a9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3178860Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77056}