[tests] drop rvv_bench support for now

Ref: llvm/llvm-project#133031 (comment)

Signed-off-by: Avimitin <[email protected]>

Author: Avimitin

tests/default.nix

@@ -123,7 +123,7 @@ let
       asm
       perf
       codegen
-      rvv_bench
+      #rvv_bench
       pytorch
       disp
       emurt-test