Update references to use multi-region bucket

[ahernank]

As part of the migration to a single-region release bucket, we need to update all public docs to point towards the multi-region one.

We need to:

• [x] Update Ag references in the vector-data guide (i.e. from gs://vo_agam_release to gs://vo_agam_release_master_us_central1 in the cloud data access and data downloads guide)
• [x] Update Af references in the vector-data guide (i.e. from gs://vo_afun_release to gs://vo_afun_release_master_us_central1)
• [ ] Check if there are any other public docs were we could also make these changes

[jonbrenas]

The PUGs also reference buckets extensively. @ahernank , should I create an issue in vector-ops similar to this one to update the PUG template (I don't think vobs-funestus has a partner_user_guide_template.ipynb yet)?