[GCU] Extend timeout to 10min (sonic-net#15434)

What is the motivation for this PR?
update timeout introduced in sonic-net#14881

How did you do it?
increase

How did you verify/test it?
E2E

tests/common/gu_utils.py

@@ -14,7 +14,7 @@
 DEFAULT_CHECKPOINT_NAME = "test"
 GCU_FIELD_OPERATION_CONF_FILE = "gcu_field_operation_validators.conf.json"
 GET_HWSKU_CMD = "sonic-cfggen -d -v DEVICE_METADATA.localhost.hwsku"
-GCUTIMEOUT = 240
+GCUTIMEOUT = 600
 
 BASE_DIR = os.path.dirname(os.path.realpath(__file__))
 FILES_DIR = os.path.join(BASE_DIR, "files")