Increase number of retries on websocket in YAML test harness.

We seem to be hitting the 4-retry cap a lot.  The question is whether waiting an
extra few seconds would help or not.

Author: bzbarsky-apple

scripts/py_matter_yamltests/matter_yamltests/websocket_runner.py

@@ -70,7 +70,7 @@ async def execute(self, request):
             return await instance.recv()
         return None
 
-    async def _start_client(self, url, max_retries=4, interval_between_retries=1):
+    async def _start_client(self, url, max_retries=5, interval_between_retries=1):
         if max_retries:
             start = time.time()
             try: