[test] make e2e chainsaw tests clean up cloud resources on failure

[moshevayner]

Resources created directly via the Linode API (NodeBalancers, Firewalls, reserved IPs, the BGP IP-holder nanode) are not tracked by chainsaw and leaked when a step failed before the test's own delete ran. Add best-effort, idempotent cleanup in the test-level catch and step cleanup blocks so these are always released, and drop redundant skipDelete / manual delete steps where chainsaw already tears the resource down.

Also: add group name for vulnerability alerts in renovate configuration

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.76%. Comparing base (bc849f7) to head (a70bbee).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #597   +/-   ##
=======================================
  Coverage   73.76%   73.76%           
=======================================
  Files          19       19           
  Lines        3045     3045           
=======================================
  Hits         2246     2246           
  Misses        538      538           
  Partials      261      261           

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