Skip testing memory swappiness for cgroupv2

[mythri-garaga]

Summary

TestSwapConfigurationTask is failing with nil pointer exception for memory swappiness in AL2023 variants. This is due to memory.swappiness is not supported in cgroupv2 - opencontainers/runtime-spec#1005.

--- FAIL: TestSwapConfigurationTask (0.77s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1492c9d]

goroutine 4096 [running]:
testing.tRunner.func1.2({0x15c29a0, 0x28a9330})
	/usr/local/go/src/testing/testing.go:1396 +0x372
testing.tRunner.func1()
	/usr/local/go/src/testing/testing.go:1399 +0x5f0
panic({0x15c29a0, 0x28a9330})
	/usr/local/go/src/runtime/panic.go:890 +0x262
github.com/aws/amazon-ecs-agent/agent/engine.TestSwapConfigurationTask(0x0?)
	/opt/amazon-ecs-agent/go/src/github.com/aws/amazon-ecs-agent/agent/engine/engine_unix_integ_test.go:894 +0xa5d

This PR change includes skipping thet memory swappiness test for cgroupv2.

Implementation details

Testing

AL2023 Integration tests checks pass

New tests cover the changes:

Description for the changelog

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[yinyic]

We may want to update our doc to call out that swappiness is not supported on ECS-Optimized AL2023 by default.

[mythri-garaga]

We may want to update our doc to call out that swappiness is not supported on ECS-Optimized AL2023 by default.

Right, will work with docs team to update this.