docs: Changed Google Analytics link to https://

We've changed the script so the auto-generated versions of these
files will now use https:// for the Google Analytics links (required
if the files are going to be moved into Piper) but the existing
files haven't had that change applied, so I'm doing it by hand.

I'll build and stage to
https://android-dot-devsite.googleplex.com/sdk/support_api_diff/...

Change-Id: Ia11114920f84101522cd4511fde6a0363675bf24