message: [Trivial] Cleanup leftover help lines for removed flags
  pivstake, -zpivstake and -reservebalance
diff: @@ -533,11 +533,8 @@ std::string HelpMessage(HelpMessageMode mode)
  strUsage += HelpMessageGroup(_("Staking options:"));
  strUsage += HelpMessageOpt("-staking=<n>", strprintf(_("Enable staking functionality (0-1, default: %u)"), 1));
  strUsage += HelpMessageOpt("-coldstaking=<n>", strprintf(_("Enable cold staking functionality (0-1, default: %u). Disabled if staking=0"), 1));
  - strUsage += HelpMessageOpt("-pivstake=<n>", strprintf(_("Enable or disable staking functionality for %s inputs (0-1, default: %u)"), CURRENCY_UNIT, 1));
  strUsage += HelpMessageOpt("-minstakesplit=<amt>", strprintf(_("Minimum positive amount (in PIV) allowed by GUI and RPC for the stake split threshold (default: %s)"),
  FormatMoney(DEFAULT_MIN_STAKE_SPLIT_THRESHOLD)));
  - strUsage += HelpMessageOpt("-zpivstake=<n>", strprintf(_("Enable or disable staking functionality for zPIV inputs (0-1, default: %u)"), 1));
  - strUsage += HelpMessageOpt("-reservebalance=<amt>", _("Keep the specified amount available for spending at all times (default: 0)"));
  if (GetBoolArg("-help-debug", false)) {
  strUsage += HelpMessageOpt("-printstakemodifier", _("Display the stake modifier calculations in the debug.log file."));
  strUsage += HelpMessageOpt("-printcoinstake", _("Display verbose coin stake messages in the debug.log file."));
  