revert: fix(security): do not allow all origins by default

This reverts commit f78a575f66ab693c3ea96ea88429ddb1a44c86c7.

This commit contains a breaking change which deviates from semver,
which we try to follow as closely as possible. That's why this change
is reverted and we will rather suggest users to upgrade to v3.

Related: https://github.com/socketio/socket.io/discussions/3741