1.9.6 Python: oneOf with primitives not working (wrong exception handler)

### What are you generating using Kiota, clients or plugins?

API Client/SDK

### In what context or format are you using Kiota?

Nuget tool

### Client library/SDK language

None

### Describe the bug

In an API that returns a OneOf of primitives and no discriminator, the codegen tries to reference a discriminator of "" , causing a value exception.

### Expected behavior

Generated ParseNode should handle no discriminator case properly

### How to reproduce

Use latest .net tool to generate api for oneOf, and try to de-serialize.

### Open API description file

### Kiota Version

1.9.6

### Latest Kiota version known to work for scenario above?(Not required)

_No response_

### Known Workarounds

Patch parse node or factory code?

### Configuration

Windows x64

### Debug output

_No response_

### Other information

Here is the generated code:

```
@staticmethod
def create_from_discriminator_value(parse_node: ParseNode) -> My_scalarValue:
if parse_node is None:
raise TypeError("parse_node cannot be null.")
try:
####### Note we look for a mapping_value but never use it
####### This next line will fail, but will throw a ValueError not an AttributeError
####### So we never get past here
child_node = parse_node.get_child_node("")
mapping_value = child_node.get_str_value() if child_node else None
except AttributeError:
mapping_value = None
result = My_scalarValue()
if boolean_value := parse_node.get_bool_value():
result.boolean = boolean_value
elif double_value := parse_node.get_float_value():
result.double = double_value
elif integer_value := parse_node.get_int_value():
result.integer = integer_value
elif string_value := parse_node.get_str_value():
result.string = string_value
return result
```

Start by reproducing the issue with the latest .NET tool using the oneOf API description shown in the report, then inspect the generated Python create_from_discriminator_value entry point. Confirm the generated ParseNode handles a primitive oneOf without a discriminator and can deserialize the response without raising a value exception.

Written by the indexing model from the issue text.