MdePkg: Fix SafeString performing assertions on runtime checks

MdePkg: Fix SafeString performing assertions on runtime checks

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2054

Runtime checks returned via status return code should not work as
assertions to permit parsing not trusted data with SafeString
interfaces.  Replace ASSERT() with a DEBUG_VERBOSE message.

Cc: Andrew Fish <afish@apple.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Bret Barkelew <bret.barkelew@microsoft.com>
Cc: Brian J. Johnson <brian.johnson@hpe.com>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Marvin Häuser <mhaeuser@outlook.de>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Vincent Zimmer <vincent.zimmer@intel.com>
Cc: Zhichao Gao <zhichao.gao@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Vitaly Cheptsov <vit9696@protonmail.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Bret Barkelew <bret.barkelew@microsoft.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>