[web] Update Blob service DELETE endpoint call

Summary:
Depends on D8396

Updated the Blob service DELETE endpoint call on Web to use the new request format.

Test Plan:
Enabled blob service uploads, selected a photo to upload to chat, then deleted it by clicking the "x" button in the photo corner.

The request was successful. Blob service logs:

Reviewers: atul, pklatka

Reviewed By: pklatka

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8397