Add registry probing timeout environment variable to the acceptance test template

[michael-valdron]

Which area/kind this issue is related to?

/area ci
/area registry

Issue Description

In #1086, optional registry probing was added to the integration test suite to delay testing in case of concurrent deployment of the target registry. This was done as a requirement to issues which occurred during staging deployments where the tests run before the registry has finished deploying.

In order to enable this feature, an environment variable PROBE_TIMEOUT needs to be added to the acceptance test template with an integer value which represents seconds to wait.

Target Date: 04-05-2023

[michael-valdron]

This is to be added to the Sprint 235 plan as this is an item for tomorrow's production promotion.