misleading display of reward accounts during pool registration

[janmazak]

Reported by @gitmachtl: Doing a pool registration, the owner count on the gui starts with #0 for the first owner, but the rewards account on the gui is shown as #1. Currently there is only one rewards account possible on cardano for a pool. The displayed #1 does not refer to ordering or count of inputs, but shows account from the key derivation path for that reward address; the users, however, are not aware of this.

We should remove the #... part there. However, the same code is used for displaying reward accounts in other places, so it needs to be investigated in more detail.