Re-use the same Chrome profile directory

[alan-knight]

We use a new chrome profile via --user-data-dir, but we give it a new one each time. That means settings don't persist, you may have to re-authenticate, etc. We should remember that we created the directory, or keep it somewhere known.

And in fact it looks like this was done for webdev for #297 and we might just need to use that information.

[jakemac53]

This was reverted in #342 so we need to understand exactly why and whether those things still matter etc before moving forward.

Definitely in favor if it doesn't cause problems.

[grouma]

The reason for the revert is here: #319 (comment)