qt: Remove HD seed reference from blank wallet tooltip

Blank descriptor wallets currently do not have HD seeds and
none can be added, so remove the reference in the tooltip.

Author: john-moffett

src/qt/forms/createwalletdialog.ui

@@ -146,7 +146,7 @@
       <item>
        <widget class="QCheckBox" name="blank_wallet_checkbox">
         <property name="toolTip">
-         <string>Make a blank wallet. Blank wallets do not initially have private keys or scripts. Private keys and addresses can be imported, or an HD seed can be set, at a later time.</string>
+         <string>Make a blank wallet. Blank wallets do not initially have private keys or scripts. Private keys and addresses can be imported using descriptors at a later time.</string>
         </property>
         <property name="text">
          <string>Make Blank Wallet</string>