community/pgbouncer: init script issues

A) The get_config function references $conffile but should actually be $cfgfile

B) Since postgresql & pgbouncer share the same socket dir by default, I'm proposing some changes so they don't fight over it's permissions and ownership.

1. Change the mode from 0755 to 1775 like the postgresql init script
2. Default the group to postgres instead of postgresql
3. Add socket_dir_user & socket_dir_group variables for cases where users run postgresql with a non-default user/group

--- /etc/init.d/pgbouncer-old   2023-09-26 19:55:25.610984470 +0000
+++ /etc/init.d/pgbouncer       2023-09-26 19:57:47.750796278 +0000
@@ -3,7 +3,9 @@
 extra_started_commands="reload"

 : ${user:="pgbouncer"}
-: ${group:="postgresql"}
+: ${group:="postgres"}
+: ${socket_dir_user:="postgres"}
+: ${socket_dir_group:="postgres"}
 : ${cfgfile:="/etc/pgbouncer/pgbouncer.ini"}
 : ${nice_timeout:=60}
 : ${force_quit:="no"}
@@ -29,7 +31,7 @@
 start_pre() {
        local socket_dir=$(get_config unix_socket_dir)
        if [ -n "$socket_dir" ]; then
-               checkpath -d -m 0755 -o postgres:postgres "$socket_dir" || return 1
+               checkpath -d -m 1775 -o $socket_dir_user:$socket_dir_group "$socket_dir" || return 1
        fi

        local logfile="$(get_config logfile)"
@@ -78,7 +80,7 @@
        local name="$1"
        local default="${2:-}"

-       if [ ! -f "$conffile" ]; then
+       if [ ! -f "$cfgfile" ]; then
                printf '%s\n' "$default"
                return 1
        fi
@@ -87,6 +89,6 @@
                  s/\s*$//;                            # trim trailing whitespaces
                  s/^['\"](.*)['\"]$/\1/;              # remove delimiting quotes
                  p
-               }" "$conffile" \
+               }" "$cfgfile" \
                | grep . || printf '%s\n' "$default"
 }