Prior to this PR, the wallet would not allow the -rescan option at
startup if pruning was enabled. This is unnecessarily restrictive. It
should be possible to rescan if pruning is enabled, as long as no blocks
have actually been pruned yet.
Remove the pruning check from WalletInit::ParameterInteraction(). If any
blocks have been pruned, that will be caught in CreateWalletFromFile().
Depends on D7090
Concludes backport of Core PR17138