[Mobile Payments] Unclear error message when backgrounding the app during a payment

[joshheald]

I looked at: cancel by backgrounding, cancel by receiving a call, cancel by turning off screen. I tried to look at cancelling by turning off wifi/connectivity via the control center (though I'm not sure I was able to actually target that or if it was just handled the same as backgrounding). I'd imagine the only issue that's specific to this PR is the grammar one -- let me know if you'd like the other two separated into their own GH issues.

• If I cancel after I pay on the Apple screen by backgrounding or closing the screen, I get an error that payment wasn't processed but the order gets marked as completed. The error looks tech-y enough that I'd imagine the merchant would be wary, but it still seems really bad that they might re-initiate payment from the buyer or think they haven't received it.
  Workflow:

1. Collect Payment > Tap to Pay
2. When you get to the Apple screen, pay using Stripe test card
3. When Apple screen goes away, background app
4. Return to Woo
5. Note error
6. Tap "Try Collecting Again"
7. Note error
8. Note order status is updated to Completed

RPReplay_Final1673553306.MP4

Originally posted by @lmischner in #8620 (comment)

Initial investigation

@lmischner Thanks for this one. When I repro it the order has actually been paid for: I checked in the Stripe dashboard and found the order was paid. I'll dig in to whether we know enough to change the error to be more descriptive, but I think given the order shows as paid correctly, it's a safe failure mode. I'll break this into a new issue and handle it separately.

Originally posted by @joshheald in #8620 (comment)