sonic-mgmt: fix port toggle timeout on many ports (#15573)

For topologies leveraging many ports, such as in
the case of t0-isolated-d128u128s2, the timeout
for non-mellanox fixed-chassis devices is a
static value and is too low for the number of
ports being configured.

In contrast, Mellanox devices use a timeout
proportional to the number of ports being
toggled. This change moves fixed-chassis
broadcom devices to use a proportional timeout
as well.

tests/common/port_toggle.py

@@ -121,14 +121,16 @@ def default_port_toggle_wait_time(duthost, port_count):
     port_down_wait_time, port_up_wait_time = 120, 180
     asic_type = duthost.facts["asic_type"]
 
-    if asic_type == "mellanox":
+    is_modular_chassis = duthost.get_facts().get("modular_chassis")
+
+    if (asic_type == "mellanox") or (asic_type == "broadcom" and not is_modular_chassis):
         if port_count <= BASE_PORT_COUNT:
             port_count = BASE_PORT_COUNT
 
         port_count_factor = port_count / BASE_PORT_COUNT
         port_down_wait_time = int(port_down_wait_time * port_count_factor)
         port_up_wait_time = int(port_up_wait_time * port_count_factor)
-    elif duthost.get_facts().get("modular_chassis"):
+    elif is_modular_chassis:
         port_down_wait_time = 300
         port_up_wait_time = 300