[refactoring] Run refactoring tests on Linux

Refactoring tests have been disabled on Linux but I can’t find a reason why that should be the case. Enable them on all platforms.

rdar://92982631

Author: ahoppen

test/refactoring/lit.local.cfg

@@ -1,7 +1,3 @@
-if 'OS=macosx' not in config.available_features:
-    config.unsupported = True
-
-else:
-    config.substitutions.append(('%refactor-check-compiles', '{} -swift-refactor {} -swift-frontend {} -temp-dir %t {}'.format(config.refactor_check_compiles, config.swift_refactor, config.swift_frontend, config.resource_dir_opt)))
-    config.substitutions.append(('%refactor', '{} {}'.format(config.swift_refactor,
-        config.resource_dir_opt)))
+config.substitutions.append(('%refactor-check-compiles', '{} -swift-refactor {} -swift-frontend {} -temp-dir %t {}'.format(config.refactor_check_compiles, config.swift_refactor, config.swift_frontend, config.resource_dir_opt)))
+config.substitutions.append(('%refactor', '{} {}'.format(config.swift_refactor,
+    config.resource_dir_opt)))