session: unload rpcd configuration before checking login

session: unload rpcd configuration before checking login

Currently, rpcd cached /etc/config/rpcd once on the first login and then
keeps checking login attempts and ACL settings against the in-memory
copy until the process is restarted.

This is not desirable as we would like added, modified or removed accounts
to be effective immediately. In order to achive this behaviour, ensure to
unload the currently loaded rpcd configuration before looking up the login
account section.

Ref: https://github.com/openwrt/luci/issues/5179
Signed-off-by: Jo-Philipp Wich <jo@mein.io>