fix: prevent autoping disable on false negative ping support check

Remove autodisable logic (prefs_set_autoping(0)) and early return in autoping
to treat intermittent false negatives from connection_supports(XMPP_FEATURE_PING).
Add one-time error display with debug features print for monitoring; warn on first failing
check without aborting to maintain functionality while investigating root cause.

tests/unittests/log/stub_log.c

@@ -26,7 +26,7 @@
 #include "log.h"
 
 void
-log_init(log_level_t filter, char* log_file)
+log_init(log_level_t filter, const char* const log_file)
 {
 }
 log_level_t