Fix warnings in msyql_lease_mgr (and likely postgresql) by #2595

Warnings introduced by #2595 (closed):

_lease_mgr.o
In file included from ../../../src/lib/dhcpsrv/lease_mgr_factory.h:11,
                 from mysql_lease_mgr.cc:15:
../../../src/lib/dhcpsrv/lease_mgr.h:979:18: warning: ‘virtual void isc::dhcp::LeaseMgr::setExtendedInfoTablesEnabled(const ParameterMap&)’ was hidden [-Woverloaded-virtual]
  979 |     virtual void setExtendedInfoTablesEnabled(const db::DatabaseConnection::ParameterMap& parameters);
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from mysql_lease_mgr.cc:16:
../../../src/lib/dhcpsrv/mysql_lease_mgr.h:1141:18: note:   by ‘virtual void isc::dhcp::MySqlLeaseMgr::setExtendedInfoTablesEnabled(bool)’
 1141 |     virtual void setExtendedInfoTablesEnabled(const bool enabled) override {
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
mysql_lease_mgr.cc: In member function ‘virtual void isc::dhcp::MySqlLeaseMgr::addRelayId6(const isc::asiolink::IOAddress&, const isc::asiolink::IOAddress&, const std::vector<unsigned char>&)’:
mysql_lease_mgr.cc:3376:51: warning: unused parameter ‘relay_id’ [-Wunused-parameter]
 3376 |                            const vector<uint8_t>& relay_id) {
      |                            ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
mysql_lease_mgr.cc: In member function ‘virtual void isc::dhcp::MySqlLeaseMgr::addRemoteId6(const isc::asiolink::IOAddress&, const isc::asiolink::IOAddress&, const std::vector<unsigned char>&)’:
mysql_lease_mgr.cc:3383:52: warning: unused parameter ‘remote_id’ [-Wunused-parameter]
 3383 |                             const vector<uint8_t>& remote_id) {
      |                             ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~