Solve the issue that the digital twin tool only generates one map tile

[donghaiwang]

Description

Removing the statement that cleans up the FilePath variable can solve the problem that only one tile is generated for the large map. If it is not commented, the FilePath memory value pointing to the xodr file is garbled when the tile is generated for the second time.

Fixes #6913

Where has this been tested?

• Platform(s): windows 10
• Python version(s): 3.7
• Unreal Engine version(s): 4.26
  

Possible Drawbacks

Whether Ubuntu works normally.

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would update our CHANGELOG.md based on your changes.

[Blyron]

This change creates a memory leaks of UOpenDriveToMap in the system as we create one on each commandlet. So we do are not merging this. we will need to find other workaround.