[E2E] Add retry to docker pull

What does this MR do and why?

We have encountered some test failures where due to what appear to be temporary networking type errors running docker pull.
These failures cause specs to fail, which don't add any valuable feedback.

Instead of this - let's introduce a retry mechanism to allow for situations where a temporary networking doesn't cause specs to fail.

Searching for failurenew with search string QA::Service::Shellout::CommandError: Command: `docker pull displays a list of open failure issues that have encountered this type of error.
Failure Search Issues

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