Step 'the "10CC5BC7" key is in the live user's public keyring' is fragile

Originally created by @bertagaz on #10501 (Redmine)

We’ve seen it failing a bit in Jenkins (2 times in September, 3 times in October).

We’re not sure of why it fails, so bertagaz will have to dig in the history but it may have been erased with the 1.7 release.
Meanwhile there’s been a bump in the retry_tor number that may have helped to workaround it.

One question raised that may help is that currently we fetch the key and check if it’s actually been fetched within 2 minutes.
Should we perhaps enforce a limit in the fetch step and cancel the fetch if it’s taking too long, then retry?
IIRC that was suggested for the Git tests.

Feature Branch: kytv/test/9095-robust-seahorse

Parent Task: #10288 (closed)