change builtin installer to upstream nix experimental #7264

Job	Run time
Test Flake Build	3m 6s
golangci-lint (ubuntu-latest)	1m 37s
build-devbox (macos-13)	49s
build-devbox (ubuntu-latest)	29s
Spell Check with Typos	8s
golangci-lint (macos-13)	7m 4s
test (not-main, ubuntu-latest, project-tests-only, 2.30.2)	10m 43s
auto-nix-install (macos-13, true)	4m 30s
test (not-main, ubuntu-latest, project-tests-only, 2.19.2)	12m 2s
test (not-main, ubuntu-latest, project-tests-only, 2.12.0)	11m 31s
auto-nix-install (macos-13, false)	5m 4s
auto-nix-install (ubuntu-latest, true)	1m 40s
test-nix-versions (macos-13, 2.15.1)	6m 47s
test (not-main, ubuntu-latest, project-tests-off, 2.30.2)	9m 5s
auto-nix-install (ubuntu-latest, false)	1m 39s
test-nix-versions (ubuntu-latest, 2.24.7)	5m 30s
test-nix-versions (macos-13, 2.24.7)	4m 0s
test (not-main, ubuntu-latest, project-tests-off, 2.12.0)	9m 44s
test-nix-versions (ubuntu-latest, 2.15.1)	2m 13s
test (not-main, ubuntu-latest, project-tests-off, 2.19.2)	10m 56s
test-nix-versions (macos-13, 2.18.0)	4m 22s
test-nix-versions (ubuntu-latest, 2.17.0)	1m 43s
test-nix-versions (ubuntu-latest, 2.16.1)	5m 59s
test-nix-versions (macos-13, 2.17.0)	3m 51s
test-nix-versions (macos-13, 2.16.1)	7m 23s
test-nix-versions (macos-13, 2.19.2)	3m 45s
test-nix-versions (ubuntu-latest, 2.19.2)	1m 40s
test-nix-versions (ubuntu-latest, 2.18.0)	1m 43s
	2h 19m 3s

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