Downgrade node-fetch back to v2 (#49592)

Author: jakebailey

package-lock.json

@@ -48,6 +48,7 @@
         "@types/mocha": "latest",
         "@types/ms": "latest",
         "@types/node": "latest",
+        "@types/node-fetch": "^2.6.2",
         "@types/q": "latest",
         "@types/source-map-support": "latest",
         "@types/xml2js": "^0.4.11",
@@ -81,7 +82,7 @@
         "mocha": "latest",
         "mocha-fivemat-progress-reporter": "latest",
         "ms": "^2.1.3",
-        "node-fetch": "^3.2.6",
+        "node-fetch": "^2.6.7",
         "prex": "^0.4.7",
         "q": "latest",
         "source-map-support": "latest",