CI/GCC: Add Fedora 44, fix build errors and threadsappend

- Add Fedora 44 to CI tests
- Fix build issues from the newer compiler. These are mostly 'char *'
  to 'const char *' conversions.
- Fix threadsappend.c test waiting for the same thread TID twice.
  This caused the test to hang on F44 (but strangely not other OSs?)

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #18478

cmd/zed/zed_event.c

@@ -238,7 +238,7 @@ _zed_event_value_is_hex(const char *name)
 		NULL
 	};
 	const char **pp;
-	char *p;
+	const char *p;
 
 	if (!name)
 		return (0);