[Mobile Payments] Review CardReaderConnectionControllerTests – fail on CI, but work locally

[joshheald]

CardReaderConnectionControllerTests are all marked as Skipped, because they fail on CI and work locally. We should investigate and fix this separately.

Also consider this PR suggestion for the mock:

          In these mocks, since we're doing multiple `if mode =` checks per method but just covering a limited number of cases, would be worth to use a switch statement and an `assertionFailure()` if falls into the default case? I'm thinking it could help with tests if we land on a state that we shouldn't. Example:

        switch mode {
        case .continueSearchingAfterConnectionFailure:
            retrySearch()
        case .cancelSearchingAfterConnectionFailure:
            cancelSearch()
        default:
            assertionFailure("Not implemented")
        }

Originally posted by @iamgabrielma in #10526 (comment)

[dangermattic]

🚫 Please add a type label (e.g. type: enhancement) and a feature label (e.g. feature: stats) to this issue.