tests: Stop copying the tool tests

No point in doing that, and the meson feature
we are using here is deprecated.

testsuite/tools/meson.build

@@ -3,12 +3,8 @@ if bash.found()
   test_env = environment()
 
   foreach t : ['simplify', 'simplify-3to4', 'validate', 'settings']
-    configure_file(output: t,
-      input: '@0@.in'.format(t),
-      copy: true,
-    )
-    test(t, bash,
-      args: t,
+    test(t,
+      find_program(t, dirs: meson.current_source_dir()),
       workdir: meson.current_build_dir(),
       protocol: 'tap',
       env: [