feat: cleanup log output for failure case

Also mark DOKKU_DISABLE_ANSI_PREFIX_REMOVAL as deprecated (it will be removed in 0.23.0 and no prefixes will be removed at that time).

plugins/common/functions

@@ -137,14 +137,14 @@ dokku_log_exit() {
 dokku_log_fail_quiet() {
   declare desc="log fail formatter"
   if [[ -z "$DOKKU_QUIET_OUTPUT" ]]; then
-    echo "$@" 1>&2
+    echo " !     $@" 1>&2
   fi
   exit 1
 }
 
 dokku_log_fail() {
   declare desc="log fail formatter"
-  echo "$@" 1>&2
+  echo " !     $@" 1>&2
   exit 1
 }