This PR contains a few smaller wallet RPC cleanups based on that we only ever operate on descriptor wallets now:
- remove the now obsolete “keypoololdest” field from the
getwalletinfo
RPC and the corresponding CWallet/ScriptPubKeyMan methods - in RPCs where potential fast wallet rescan is documented, remove the “descriptor wallet” mentions (back then introduced in commit ca48a4694f73e5be8f971ae482ebc2cce4caef44, PR #25957)
- for the
createwallet
RPC examples, remove the “descriptors” parameters that always have to be true now (proposed in #31250 (review); corresponds to 86de8c1668005304b2c630ca2ad4a8ca8e348e90, PR #32544 which did the same for functional tests)