Revert Node.js 20.6.0 bug workaround (#15965)

babel.config.js

@@ -303,15 +303,6 @@ module.exports = function (api) {
         ].map(normalize),
         plugins: [pluginImportMetaUrl],
       },
-      // See comment in the plugin
-      convertESM && {
-        test: [
-          "./packages/babel-core/src/index.ts",
-          "./packages/babel-types/src/index.ts",
-          "./packages/babel-traverse/src/index.ts",
-        ],
-        plugins: [pluginInjectErrorBugNode_20_6_0],
-      },
       {
         test: sources.map(source => normalize(source.replace("/src", "/test"))),
         plugins: [
@@ -963,45 +954,3 @@ function pluginReplaceNavigator({ template }) {
     },
   };
 }
-
-// Workaround for https://github.com/nodejs/node/issues/49497, since
-// Node.js is taking ages to release the fix.
-// This bug only affects CJS packages that are imported from ESM. We only apply
-// it to packages that have cycles in their entrypoint. They can be easily
-// caught by our CI in ESM mode on Node.js 20.6.0:
-// - @babel/core
-// - @babel/types
-// - @babel/traverse
-//
-// We will remove this workaround after one week that Node.js 20.6.1 has been
-// released, so that all CIs using `node:latest` will be using the new version.
-function pluginInjectErrorBugNode_20_6_0({ template }) {
-  const flag = "___internal__alreadyRunning";
-
-  return {
-    post({ path }) {
-      path.unshiftContainer(
-        "body",
-        // We use `"${flag}" + ""` so that the Node.js ESM-CJS
-        // integration does not detect it as an export.
-        template.statement.ast`
-          if (typeof process === "object" && process.version === "v20.6.0") {
-            if (exports["${flag}" + ""]) return;
-            Object.defineProperty(exports, "${flag}", {
-              value: true,
-              enumerable: false,
-              configurable: true,
-            });
-          }
-        `
-      );
-      path.pushContainer(
-        "body",
-        template.statement.ast`
-          if (typeof process === "object" && process.version === "v20.6.0")
-            delete exports["${flag}" + ""];
-          `
-      );
-    },
-  };
-}