Drop the undici shim type test from the TypeScript 5 import allowlist

The test checks the shims with the TypeScript 7 checker and no longer
imports typescript5, so test-ts7 reported its allowlist entry as stale.

scripts/test-ts7.mjs

@@ -30,7 +30,6 @@ const ALLOWED_TYPESCRIPT5_IMPORTS = new Set([
   "packages/compiler/src/library/semantic-source.ts",
   "packages/compiler/test/ts7/harness.ts",
   "packages/compiler/test/ts7/resolver-parity.test.ts",
-  "packages/compiler/test/undici-shim-types.test.ts",
 ]);
 
 function sourceFilesUnder(dir) {