[llvm-dwp] Fix FoundCUUnit problem on soft-stop with DWARF5 (llvm#169783)

Currently, when a 'soft-stop' is triggered due to debug_info overflow,
there is an additional check for Dwarf5 to verify if the dwo contains a
split_compile unit (CU). However, since split_type units (TUs) are
typically placed before CUs in debug_info for Dwarf5, if an overflow is
detected within a TU causing an early break, the logic incorrectly
assumes this DWO lacks a CU and triggers an error.

Since the overflowing DWO will be discarded anyway, this validation is
redundant. This patch tries to fix this by removing the CU check during
a soft-stop.

Before this patch：
```
llvm-dwp main.dwo -continue-on-cu-index-overflow=soft-stop -o main.dwp
warning: debug_info Section Contribution Offset overflow 4G. Previous Offset 4294967271, After overflow offset 38.
error: no compile unit found in file: main.dwo
```
After：
```bash
llvm-dwp main.dwo -continue-on-cu-index-overflow=soft-stop -o main.dwp
warning: debug_info Section Contribution Offset overflow 4G. Previous Offset 4294967271, After overflow offset 38.
```

Author: Jinjie-Huang

llvm/lib/DWP/DWP.cpp

@@ -826,9 +826,7 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
                     "debug_info", OverflowOptValue, AnySectionOverflow))
               return Err;
             if (AnySectionOverflow) {
-              if (Header.Version < 5 ||
-                  Header.UnitType == dwarf::DW_UT_split_compile)
-                FoundCUUnit = true;
+              FoundCUUnit = true;
               break;
             }
           }