meta: remove `initializeCommand` from devcontainer

PR-URL: https://github.com/nodejs/node/pull/53137
Fixes: https://github.com/nodejs/node/issues/53129
Reviewed-By: Vinícius Lourenço Claro Cardoso <contact@viniciusl.com.br>
Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>
Reviewed-By: James M Snell <jasnell@gmail.com>

.devcontainer/devcontainer.json

@@ -7,7 +7,6 @@
     "visualstudioexptteam.vscodeintellicode"
   ],
   "image": "nodejs/devcontainer:nightly",
-  "initializeCommand": "docker system prune -f -a",
   "settings": {
     "terminal.integrated.profiles.linux": {
       "zsh (login)": {