disallow redirects in the Guzzle client for JSONAPI requests

Problem/Motivation

getJsonApiClient() doesn't explicitly disallow redirects, and it appears that Guzzle allows them by default.

This causes big problems with the Entity Pull form. I keep seeing the flood table getting sets of requests with the same timestamp, which are causing the client API user to be flood-blocked.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes