test failed in CI: test_disks_detached_when_instance_destroyed

[hawkw]

This test failed on a CI run on pull request #9320:
https://github.com/oxidecomputer/omicron/runs/54221564739

Log showing the specific test failure:
https://buildomat.eng.oxide.computer/wg/0/details/01K8XWTCQMMPPN3XXYK7939N7W/z4Ak1eq0Nr77XgsLq7UwrmObPFmJAebgbQn5GnRY3KsmsYaQ/01K8XWTWR7HHA95GKSV7F05JH7#S7827

Excerpt from the log showing the failure:

 test integration_tests::instances::test_disks_detached_when_instance_destroyed ... FAILED

    failures:

    failures:
        integration_tests::instances::test_disks_detached_when_instance_destroyed

    test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 476 filtered out; finished in 362.82s
    
  stderr ───
    log file: /var/tmp/omicron_tmp/test_all-5f88b37630518445-test_disks_detached_when_instance_destroyed.25759.0.log
    note: configured to log to "/var/tmp/omicron_tmp/test_all-5f88b37630518445-test_disks_detached_when_instance_destroyed.25759.0.log"
    DB URL: postgresql://root@[::1]:58704/omicron?sslmode=disable
    DB address: [::1]:58704
    log file: /var/tmp/omicron_tmp/test_all-5f88b37630518445-test_disks_detached_when_instance_destroyed.25759.2.log
    note: configured to log to "/var/tmp/omicron_tmp/test_all-5f88b37630518445-test_disks_detached_when_instance_destroyed.25759.2.log"

    thread 'integration_tests::instances::test_disks_detached_when_instance_destroyed' panicked at nexus/tests/integration_tests/instances.rs:7697:19:
    instance 599ae8dd-be5c-4696-a166-6c788b0616e9 did not transition to Stopped after 320s: timed out after 320.676436008s
    stack backtrace:
...