chore: remove yarn.lock and packageManager field (patternfly#855)

This project uses npm with package-lock.json. Removing the
unused yarn.lock and conflicting packageManager field.

Author: nicolethoen

package.json

@@ -86,6 +86,5 @@
     "@patternfly/react-drag-drop": "^6.0.0",
     "@patternfly/react-tokens": "^6.0.0",
     "sharp": "^0.34.0"
-  },
-  "packageManager": "yarn@4.10.3+sha512.c38cafb5c7bb273f3926d04e55e1d8c9dfa7d9c3ea1f36a4868fa028b9e5f72298f0b7f401ad5eb921749eb012eb1c3bb74bf7503df3ee43fd600d14a018266f"
+  }
 }