[7.x] [kbn/optimizer] mangle variables in optimizer bundles (#112435)…

… and (#113119) (#112498)

* [kbn/optimizer] mangle variables in optimizer bundles (#112435)

Co-authored-by: spalger <spalger@users.noreply.github.com>

* [optimizer] keep classnames to support constructor.name (#113119)

Co-authored-by: spalger <spalger@users.noreply.github.com>
(cherry picked from commit 6612f2b)

Co-authored-by: Spencer <email@spalger.com>
Co-authored-by: spalger <spalger@users.noreply.github.com>

package.json

@@ -811,7 +811,7 @@
     "tar-fs": "^2.1.0",
     "tempy": "^0.3.0",
     "terser": "^5.7.1",
-    "terser-webpack-plugin": "^2.1.2",
+    "terser-webpack-plugin": "^4.2.3",
     "tough-cookie": "^4.0.0",
     "ts-loader": "^7.0.5",
     "ts-morph": "^9.1.0",