dns_gandi_livedns: load saved credentials in rm

Since 329dab9a (3.1.3) the token/key is saved with
_saveaccountconf_mutable, but only _add read it back. rm runs in its
own subshell, so on cron renewal it called the API unauthenticated;
the 401 body has no "code": 401, so _get_root took the first probe as
the zone and the TXT record was never removed.

Fixes #7347

dnsapi/dns_gandi_livedns.sh

@@ -59,6 +59,13 @@ dns_gandi_livedns_rm() {
   fulldomain=$1
   txtvalue=$2
 
+  GANDI_LIVEDNS_KEY="${GANDI_LIVEDNS_KEY:-$(_readaccountconf_mutable GANDI_LIVEDNS_KEY)}"
+  GANDI_LIVEDNS_TOKEN="${GANDI_LIVEDNS_TOKEN:-$(_readaccountconf_mutable GANDI_LIVEDNS_TOKEN)}"
+  if [ -z "$GANDI_LIVEDNS_KEY" ] && [ -z "$GANDI_LIVEDNS_TOKEN" ]; then
+    _err "No Token or API key (deprecated) specified for Gandi LiveDNS."
+    return 1
+  fi
+
   _debug "First detect the root zone"
   if ! _get_root "$fulldomain"; then
     _err "invalid domain"