Revert "fix(deepdoc): keep zero and false Excel cells in __call__" (#16366)

Reverts infiniflow/ragflow#16318

deepdoc/parser/excel_parser.py

@@ -283,7 +283,7 @@ class RAGFlowExcelParser:
             for r in list(rows[1:]):
                 fields = []
                 for i, c in enumerate(r):
-                    if c.value is None:
+                    if not c.value:
                         continue
                     t = str(ti[i].value) if i < len(ti) else ""
                     t += ("：" if t else "") + str(c.value)