Clear out all the ReadWrite transactions that are only necessary because of images

[ikesau]

Grep // TODO: this transaction is only RW because somewhere inside it we fetch images and despair

Syncing images any time you touch them sounded nice, but it's turned out to be quite the anti-pattern.

#3496 updates loadGdocFromGdocBase so that we only write to the DB if contentSource=gdocs, but I think we need to go further and break that function into two.

A readwrite version, and a readonly version (which is all we need in most of the codebase, thereby clearing out all the TODO comments.)

It may be worth going even further and restructuring things so that the images table + S3 only update when an author hits publish, because we're kind of half-trying to do that, but it's not particularly consistent.

owid-grapher/adminSiteServer/apiRouter.ts

Line 2283 in d4cf8ed

await updateGdocContentOnly(trx, id, gdoc)

[danyx23]

Probably makes sense to tackle this when we do #2485