Add non-root system-id selection

[nullmonk]

Let non-root imix beacons use a /var/tmp (persistent on reboot) system-id. Move that system-id to /etc/ whenever a root beacon is run

/kind feature

[github-actions]

Summary

Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
2959    ±0	2959    ±0	0    ±0	0    ±0	0    ±0	0    ±0	1ms    ±0

Previous Results

Build 🏗️	Result 🧪	Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
#407	✅	2959	2959	0	0	0	0	29.9s

Insights

Average Tests per Run	Total Flaky Tests	Total Failed	Slowest Test (p95)
2959	0	0	45.9s

Slowest Tests

Test 📝	Results 📊	Duration (avg) ⏱️	Duration (p95) ⏱️
eldritch: random::string_impl::tests::test_string_uniform	3	43.2s	45.9s
eldritch: random::string_impl::tests::test_string_uniform	3	43.2s	45.9s
eldritch: random::string_impl::tests::test_string_uniform	3	43.2s	45.9s
eldritch: random::string_impl::tests::test_string_length	3	6.6s	8.5s
eldritch: random::string_impl::tests::test_string_length	3	6.6s	8.5s
eldritch: random::string_impl::tests::test_string_length	3	6.6s	8.5s
eldritch-stdlib-tests: tests::test_all_tomes	3	5.2s	5.4s
eldritch-stdlib-tests: tests::test_all_tomes	3	5.2s	5.4s
eldritch-stdlib-tests: tests::test_all_tomes	3	5.2s	5.4s
eldritch: sys::dll_reflect_impl::tests::test_dll_reflect_starlark	1	5.4s	5.4s

_{🎉 No failed tests in this run. | 🍂 No flaky tests in this run.}

Github Test Reporter by CTRF 💚

🔄 This comment has been updated

[hulto]

LGTM