Skip LoadSNSspec.txt in system test LoadLotsOfFiles (#39220)

skip trying to load LoadSNSspec.txt since LoadSpec is not registered as a file loader

Author: backmari

Testing/SystemTests/tests/framework/LoadLotsOfFiles.py

@@ -41,6 +41,7 @@
     "batch_input.csv",
     "mar11015.msk",
     "LET_hard.msk",  # It seems loade does not understand it?
+    "LoadSNSspec.txt",  # LoadSpec is not registered as a file loader
     "MASK.094AA",
     "MASKSANS2D_094i_RKH.txt",
     "MASKSANS2D.091A",