[#3949] Do not add suffix to qualifed host names

[#3949] Do not add suffix to qualifed host names

/src/bin/dhcp4/tests/host_unittest.cc
/src/bin/dhcp6/tests/host_unittest.cc
    Updated tests

/src/lib/dhcpsrv/d2_client_mgr.cc
    D2ClientMgr::qualifyName() - don't add suffix to
    names that end with a dot.

/src/lib/dhcpsrv/d2_client_mgr.h
    D2ClientMgr::adjustDomainName() - strip trailing dots
    from T::PARTIAL FQDNs before calling qualifyName()

/src/lib/dhcpsrv/tests/d2_client_unittest.cc
    TEST_F(D2ClientMgrParamsTest, qualifyName) - updated