fix(dns_infomaniak): correctly detect API errors (#7048)

The add/rm success check never rejected anything: for any non-empty API
response it always reported "Record added"/"Record deleted" and returned
0, so the _err branch was dead code. A valid key looked fine only because
the API call genuinely created the record; an invalid key returning
{"result":"error"} produced the same "Record added" output even though
nothing was created.

Root cause, in:
  if [ -n "$response" ]; then
    if [ ! "$(echo "$response" | _contains '"result":"success"')" ]; then

  - _contains() ignores stdin (it reads only $1 and $2), so the piped
    "$response" was discarded.
  - The pattern '"result":"success"' was passed as $1 (the haystack),
    leaving $2 (the needle) empty, so it ran:
      echo '"result":"success"' | grep -- "" >/dev/null 2>&1
    grep with an empty pattern always matches.
  - That grep output is redirected to /dev/null, so the command
    substitution always captured "", making [ ! "" ] always true.

Fix: call _contains "$response" '"result":"success"' directly and branch
on its exit code, so error responses now correctly fail (return 1).

Co-authored-by: neil <github@neilpang.com>

dnsapi/dns_infomaniak.sh

@@ -85,12 +85,10 @@ dns_infomaniak_add() {
 
   # API call
   response=$(_post "$data" "${INFOMANIAK_API_URL}/2/zones/${zone}/records")
-  if [ -n "$response" ]; then
-    if [ ! "$(echo "$response" | _contains '"result":"success"')" ]; then
-      _info "Record added"
-      _debug "response: $response"
-      return 0
-    fi
+  if _contains "$response" '"result":"success"'; then
+    _info "Record added"
+    _debug "response: $response"
+    return 0
   fi
   _err "Could not create record."
   _debug "Response: $response"
@@ -169,11 +167,10 @@ dns_infomaniak_rm() {
 
   # API call
   response=$(_post "" "${INFOMANIAK_API_URL}/2/zones/${zone}/records/${record_id}" "" DELETE)
-  if [ -n "$response" ]; then
-    if [ ! "$(echo "$response" | _contains '"result":"success"')" ]; then
-      _info "Record deleted"
-      return 0
-    fi
+  if _contains "$response" '"result":"success"'; then
+    _info "Record deleted"
+    _debug "response: $response"
+    return 0
   fi
   _err "Could not delete record."
   _debug "Response: $response"