[bugfix] prevent UnicodeDecodeError errors when opening log file in feature_init.py

open log file as a raw byte stream in feature_init.py
(fixes #23989)

Author: sogoagain

test/functional/feature_init.py

@@ -93,7 +93,7 @@ def check_clean_start():
             additional_lines = random.randint(1, num_total_logs)
             self.log.debug(f"Starting node and will exit after {additional_lines} lines")
             node.start(extra_args=['-txindex=1'])
-            logfile = open(node.debug_log_path, 'r', encoding='utf8')
+            logfile = open(node.debug_log_path, 'rb')
 
             MAX_SECS_TO_WAIT = 10
             start = time.time()