tests: cleanup stale packet namespace automatically (#10245)

* tests: cleanup stale packet namespace automatically

Cancelled job on Gitlab can produce stale VMs as the delete playbook
will never be executed. This commits allow removing old vms by getting
all the namespace created from the same branch with an older pipeline
id.

Signed-off-by: Arthur Outhenin-Chalandre <arthur.outhenin-chalandre@proton.ch>

* tests: cleanup stale packet namespace after 2 hours

This ensure that we don't have any packet namespace remaining for more
than 2 hours. All the jobs complete usually within 30min-1hour so 2
hours is enough to detect a stale namespace.

Signed-off-by: Arthur Outhenin-Chalandre <arthur.outhenin-chalandre@proton.ch>

* tests: ignore vm cleanup failure

Signed-off-by: Arthur Outhenin-Chalandre <arthur.outhenin-chalandre@proton.ch>

* tests: use pipeline_id var instead of fetching namespace for cleanup packet vm

Signed-off-by: Arthur Outhenin-Chalandre <arthur.outhenin-chalandre@proton.ch>

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Signed-off-by: Arthur Outhenin-Chalandre <arthur.outhenin-chalandre@proton.ch>