Makes testinfra SSH calls more resilient
Makes testinfra SSH calls more resilient

The config test suite passes locally against the AWS scenario reliably;
in CI, however, there are sporadic connectivity issues. Let's instruct
testinfra to retry failed connections, to make sure the tests are
running well.

conorsch/securedrop,heartsucker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,conorsch/securedrop,ehartsuyker/securedrop,conorsch/securedrop,heartsucker/securedrop,conorsch/securedrop,ehartsuyker/securedrop,conorsch/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop