Backport of ui: fix zero memory utilization bug on systems using cgroups v2 into release/1.3.x

[hc-github-team-nomad-core]

Backport

This PR is auto-generated from #13670 to be assessed for backporting due to the inclusion of the label backport/1.3.x.

The below text is copied from the body of the original PR.

---

A quick band-aid fix for #13023. On systems using cgroups v2, the MemoryStats struct no longer reports .RSS, but rather .Usage. Kind of just assuming they mean the same thing.

The fix here is to just check if .Usage exists and if so use that, otherwise fallback to the .RSS field.

"MemoryStats": {
	"RSS": 0,
	"Cache": 0,
	"Swap": 0,
	"MappedFile": 0,
	"Usage": 98656256,
	"MaxUsage": 0,
	"KernelUsage": 0,
	"KernelMaxUsage": 0,
	"Measured": [
		"Cache",
		"Swap",
		"Usage"
	]
},

@philrenaud @ChaiWithJai

Fixes #13023

[github-actions]

Ember Test Audit comparison

	release/1.3.x	150075c	change
passes	1286	1286	0
failures	2	2	0
flaky	0	0	0
duration	000ms	000ms	-000ms

[github-actions]

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