Fix moduleNameMapper to not resolve .wasm.js to .js

Fixes misskey-dev#9767

Undici [tries to import `./llhttp/llhttp.wasm.js`](https://github.com/nodejs/undici/blob/e155c6db5cec9bc577d548fa7c7378013631c79c/lib/client.js#L342) which is currently broken by the (hacky) module name mapper.

packages/backend/jest.config.cjs

@@ -83,7 +83,14 @@ module.exports = {
 
 	// A map from regular expressions to module names or to arrays of module names that allow to stub out resources with a single module
 	moduleNameMapper: {
-		"^@/(.*?).js": "<rootDir>/src/$1.ts",
+		// Do not resolve .wasm.js to .wasm by the rule below
+		'^(.+)\\.wasm\\.js$': '$1.wasm.js',
+		// SWC converts @/foo/bar.js to `../../src/foo/bar.js`, and then this rule
+		// converts it again to `../../src/foo/bar` which then can be resolved to
+		// `.ts` files.
+		// See https://github.com/swc-project/jest/issues/64#issuecomment-1029753225
+		// TODO: Use `--allowImportingTsExtensions` on TypeScript 5.0 so that we can
+		// directly import `.ts` files without this hack.
 		'^(\\.{1,2}/.*)\\.js$': '$1',
 	},
 
@@ -112,7 +119,7 @@ module.exports = {
 	// resetModules: false,
 
 	// A path to a custom resolver
-	resolver: './jest-resolver.cjs',
+	// resolver: './jest-resolver.cjs',
 
 	// Automatically restore mock state between every test
 	restoreMocks: true,