feat(download): Allow downloading combined files from any mirror

Background: Over at Geocode Earth we've now set up our own mirror of WOF
data that sits a bit closer to our servers. It lets us kick off new
builds, etc a bit faster than downloading from the _public_ WOF server
we host on Bunny CDN.

When trying that out today, I noticed some logic from ~2 years ago was
causing the download script to download not only the combined,
planet-level files, but every country file as well.

I think this logic dates back from when we were transitioning off
`dist.whosonfirst.org`, which as I recall didn't have combined files
(they had recently moved from one giant Github repo to the per-country
repository setup that exists today).

As far as I can tell this logic isn't needed any more, it's fair to
assume any WOF mirror would follow the same directory structure as the
primary mirror that we host, meaning it would have both combined and
country-level files. That's what this PR now allows for.

utils/download_sqlite_all.js

@@ -44,8 +44,7 @@ function download(callback) {
     const countries = getCountriesToDownload();
     return (e) => {
       if (countries.length === 0) {
-        // This is specific to geocode earth, it will select global sqlites
-        return COMBINED_REGEX.test(e.name_compressed) || wofDataHost !== DATA_GEOCODE_EARTH_URL;
+        return COMBINED_REGEX.test(e.name_compressed);
       }
       // This will download sqlites with the selected country code
       return COUNTRY_REGEX.test(e.name_compressed) && countries.some(c => e.name_compressed.indexOf(`-${c}-latest`) >= 0);