bug: openy_map pins break when map isn't on a top level page

[froboy]

Observed behavior

https://github.com/ymcatwincities/openy/pull/2595#issuecomment-977741769 https://github.com/ymcatwincities/openy/issues/1256

There's some conflict between whether the openy_map module should store relative or absolute paths. Using the map either when Drupal is installed in a subfolder or when the map isn't at a top level page (/about/locations instead of /locations, for example) results in broken pins.

Expected behavior

The Open Y Location Finder map should be able to be used with any base path and on any page in a site hierarchy.

[froboy]

example with map at a different url.