update how to request access for google analytics & tag manager

On the tech stack page there were mentions of how to request access for google analytics and google tag manager.

1. the instructions were out of date
2. these were the only two tools that had this type of instructions because it was pulled from legacy process.

I have removed the mentions entirely for consistency with the rest of the tools on this page.

Also added instruction for requesting access @ top of page with cross link to the Access Request page