UI: Reset the system and refetch namespaces with every token change

[DingoEatingFuzz]

Fixes #6492

Curiously, when I attempted to fix the reported issue, I couldn't find the root cause. For some reason, despite the namespace being in localStorage and in the system service, it couldn't be looked up via this.get('system.activeNamespace.id'). It would just be undefined. More curious yet, this.get('system.activeNamespace').id worked.

While poking at that, I noticed that the namespaces list would be stale after a token change, since different tokens will allow access to different sets of namespaces. Fixing that issue coincidentally fixed the reporting issue. I'll take it ¯_(ツ)_/¯

[github-actions]

Ember Asset Size action

As of da02410

Files that got Bigger 🚨:

File	raw	gzip
nomad-ui.js	+60 B	+10 B

Files that stayed the same size 🤷‍:

File	raw	gzip
vendor.js	0 B	0 B
nomad-ui.css	0 B	0 B
vendor.css	0 B	0 B

[github-actions]

Ember Test Audit comparison

	master	da02410	change
passes	1287	1288	+1
failures	0	0	0
flaky	0	0	0
duration	5m 55s 751ms	6m 00s 788ms	+05s 037ms

[backspace]

Thanks for figuring this out! That’s a strange discrepancy with the property being undefined but I’m glad the problem disappeared with the clearing of namespaces 🥳

[github-actions]

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