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

module/zfs/dsl_dir.c

@@ -417,7 +417,7 @@ dsl_dir_namelen(dsl_dir_t *dd)
 static int
 getcomponent(const char *path, char *component, const char **nextp)
 {
-	char *p;
+	const char *p;
 
 	if ((path == NULL) || (path[0] == '\0'))
 		return (SET_ERROR(ENOENT));