Remove unused blob upload partial

What does this MR do and why?

In a previous commit and issue, we migrated the blob upload view to vue, so the haml is no longer necessary.

Resolves #363972 (closed) as well

Note: @jerasmus confirmed that the spec tests can be removed, and the rest will be cleaned up in #356960 (closed)

How to set up and validate locally

On the Project Repository page, click on the + > Upload file. This still works as it's using the vue version.

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