Update location targeting on an existing Google campaign

Device targeting on Google is editable through targeting.devices on the ad route. Locations are not: any other targeting field on an existing Google campaign returns a 400, so a campaign that targets the wrong region has to be recreated or
fixed in Google Ads.

Why it matters to us: region is the single most common thing a local business wants to change. An installer who adds a second service area, or someone who realises they're paying for clicks two provinces away, is making a small correction,
not starting over. "Delete this campaign and build a new one" loses the history and the learning, and it's a lot to ask for what feels like editing one line.

What would help: allow updating the location set on an existing campaign, even with the same constraint that already applies elsewhere, where an update replaces the full set rather than merging it. We can work with "send the complete list
you want to keep"; we already do exactly that for LinkedIn targeting.