Memory exhaustion test case fails intermittently

[bmridul]

Description

platform_tests/test_memory_exhaustion.py fails intermittently. The test allocates all the memory on the box and then expects a kernel panic to trigger as panic_on_oom is enabled. The test script depletes the memory on the system in a few seconds. Subsequently system slows down and is not responsive for many minutes. Eventually Linux triggers kernel panic. The issue is that the test expects the panic to get triggered in 10 mts. However in certain cases, it takes 20+ minutes for Kernel to raise OOM condition causing the test to fail intermittently.

Steps to reproduce the issue:

1. Run the test case - https://github.com/sonic-net/sonic-mgmt/blob/master/tests/platform_tests/test_memory_exhaustion.py
2. Check the time it takes to complete the test.

[bmridul]

Issue is fixed with PR #11738