openbsd: properly set daemon workdir, use default rc_start, set MIX_ENV in login.conf

Setting the MIX_ENV variable in rc_pre() isn't possible, because the
environment doesn't persist between rc_pre and rc_start(). This way we
can also ditch the custom rc_start() function in favor of the default
one which is just:

rc_start() {
	rc_exec "${daemon} ${daemon_flags}
}

installation/openbsd/rc.d/pleroma

@@ -13,8 +13,7 @@
 daemon="/usr/local/bin/elixir"
 daemon_flags="--erl \"-detached\" -S /usr/local/bin/mix phx.server"
 daemon_user="_pleroma"
-
-env="MIX_ENV=prod"
+daemon_execdir="/home/_pleroma/pleroma"
 
 . /etc/rc.d/rc.subr
 
@@ -25,10 +24,6 @@ rc_check() {
 	pgrep -q -U _pleroma -f "phx.server"
 }
 
-rc_start() {
-	rc_exec "cd pleroma; export ${env}; ${daemon} ${daemon_flags}"
-}
-
 rc_stop() {
 	pkill -q -U _pleroma -f "phx.server"
 }