UAT not considering remote root

It seems like WriteFileList (TempStorage.cs) is not respecting the enginePath as set from horde context. _localDir in TempStorage.cs seems to be based off of the RootDir (details here).

Proposed fix is to base this _localRoot off of the Unreal.EngineDirectory instead of attempting to concatenate with rootDir.

TempStorage Storage = new TempStorage(RootDir, DirectoryReference.Combine(Unreal.EngineDirectory, "Saved", "BuildGraph"), (SharedStorageDir == null) ? null : new DirectoryReference(SharedStorageDir), bWriteToSharedStorage);