Remove unused node memwatch (#12955)

Author: rchiodo

package-lock.json

@@ -3299,7 +3299,6 @@
         "@nteract/transform-vega": "^6.0.3",
         "@nteract/transforms": "^4.4.7",
         "@phosphor/widgets": "^1.9.3",
-        "@raghb1/node-memwatch": "^3.0.1",
         "@sinonjs/fake-timers": "^6.0.1",
         "@testing-library/react": "^9.4.0",
         "@types/ansi-regex": "^4.0.0",