qml: starting lnurl flow corrupts "Send" state

[SomberNight]

Steps:

1. in qml, open a wallet, be on history screen
2. click Send - scan QR code of an lnurl-pay (see example at the bottom)
3. "LNURL Payment request" popup appears (where user could e.g. specify exact amount or enter message)
   • cancel popup by clicking outside or using system Back button
4. now on history screen again, click Send
   • scan QR code of a bolt11 invoice
5. BUG: observe that the app enters the state of final confirmation for paying the bolt11 (e.g. PIN prompt)
   • instead we should just show the decoded bolt11 invoice
   • step 3 must be leaving some side-effect around

I noticed this when testing #10340 (with fingerprint enabled and config PIN set). In that case this is a critical bug: after scanning a bolt11 QR code, the user is prompted for the fingerprint and if they touch their finger, the payment is instantly sent -- without showing even the payment amount to the user.