Porting 14827 to 202405: Enabling bfd scale and associated fixes.

[rraghav-cisco]

Description of PR

bfd_scale test was skipped for cisco-8000 till now. This PR addresses the gap, and enables it. The default is still 128. If we need to run bigger numbers, we need to pass "-e --num_sessions_scale=400" argument.

Caveat:
The ptf container is unable to handle more than ~700 sessions. This is not a limitation on the DUT. When running with 1024 sessions, the PTF pretty much hangs, and the script errors out with the error below. This needs to be seperately fixed.

        # Raise exception if host(s) unreachable
        # FIXME - if multiple hosts were involved, should an exception be raised?
        if callback.unreachable:
>           raise AnsibleConnectionFailure(
                "Host unreachable in the inventory",
                dark=callback.unreachable,
                contacted=callback.contacted,
            )
E           pytest_ansible.errors.AnsibleConnectionFailure: Host unreachable in the inventory

arg_value  = ['/data/ansible/library']
args       = ['pytest-ansible', 'ptf_ucs-m5-2', '--connection=smart', '--become', '--become-method=sudo', '--become-user=root', ...]
argument   = 'module-path'
callback   = <pytest_ansible.module_dispatcher.v213.ResultAccumulator object at 0x7fdbdc90c790>
complex_args = {'_raw_params': 'bfdd-control stop'}
extra_hosts = []
hosts      = [ptf_ucs-m5-2]
kwargs     = {'inventory': <ansible.inventory.manager.InventoryManager object at 0x7fdbdc10c820>, 'loader': <ansible.parsing.datalo...ss': None}, 'stdout_callback': <pytest_ansible.module_dispatcher.v213.ResultAccumulator object at 0x7fdbdc90c790>, ...}
kwargs_extra = {}
module_args = ('bfdd-control stop',)
no_hosts   = False
play       = pytest-ansible
play_ds    = {'become': True, 'become_user': 'root', 'gather_facts': 'no', 'hosts': 'ptf_ucs-m5-2', ...}
play_extra = None
self       = <pytest_ansible.module_dispatcher.v213.ModuleDispatcherV213 object at 0x7fdbdc10c670>
tqm        = <ansible.executor.task_queue_manager.TaskQueueManager object at 0x7fdbdc9755b0>
verbosity  = None
verbosity_syntax = '-vvvvv'

Summary:
Enable bfd_scale test for cisco-8000.

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 202012
• 202205
• 202305
• 202311
• 202405

Approach

What is the motivation for this PR?

Need to enable bfd scale test for cisco-8000.

How did you do it?

Removed the skip condition, and fixed some issues while running bigger numbers than 128.

How did you verify/test it?

Ran it on my TB.