Fix pydantic alias issue

This PR removes the alias as pydantic requires the usage of the alias when initializing the class not the original name which prevents this code from working.

```py
cosmosdb_settings = AzureCosmosDBSettings.create(
                env_file_path=env_file_path,
                connection_string=cosmos_connstr,
            )
```

python/semantic_kernel/connectors/memory/azure_cosmosdb/azure_cosmosdb_settings.py

@@ -21,4 +21,4 @@ class AzureCosmosDBSettings(KernelBaseSettings):
     env_prefix: ClassVar[str] = "COSMOSDB_"
 
     api: str | None = None
-    connection_string: SecretStr | None = Field(None, alias="AZCOSMOS_CONNSTR")
+    connection_string: SecretStr | None = None