feat: allow skipping the install trigger when installing a plugin

During docker image generation, certain folders either do not exist or are symlinked in an odd fashion, causing the install trigger to fail. This is not the case at runtime, so we should defer the install trigger until container start and provide a method of skipping it when generating a docker image.

Closes #7308

docker/etc/my_init.d/10_dokku_init

@@ -86,7 +86,7 @@ main() {
   fi
 
   # run core install triggers to force create any folders that may be missing
-  dokku plugin:install --core
+  dokku plugin:install
 
   if [[ -n "$DOKKU_HOSTNAME" ]]; then
     echo "dokku dokku/hostname string $DOKKU_HOSTNAME" | debconf-set-selections