MdeModulePkg/DebugLibReportStatusCode: Fix hang if format is too long

MdeModulePkg/DebugLibReportStatusCode: Fix hang if format is too long

The previous commit 137ed15511e2045a7333e33ae7f1e873ce1961dd
* MdeModulePkg/DebugLib: Print partial when format string is too long
copies partial format string to DEBUG_INFO buffer but when parsing
the format modifier, the original format string is still used.

The patch fixes this issue.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>