Cleanup dataset_downloader for HM3D v0.2

[aclegg3]

Motivation and Context

Follow-up to #1910 which updated paths for HM3D Semantics v0.2.
As pointed out by @srama2512, some download paths were changed for HM3D's annotated v0.2 scenes which were not correctly updated in the previous PR.

Primary changes:

• correctly reference v0.2 of non-semantic HM3D.
• remove obj+mtl from habitat downloader (these were not updated with v0.2 and have no reason to be connected to Habitat).
• clean up uid tags to no longer reference version (like all other data-sources)

How Has This Been Tested

Local testing in progress.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.

[ykarmesh]

I tried adding @srama2512 as a reviewer but I am unable to do that