[Maps] time-based mvt data is refreshed frequently for .mvt scaling-type

[thomasneirynck]

When scaling-type is .mvt for an index-pattern with time-based data, it is constantly refreshed under panning/zooming when the time-frame is relative. This causes a flash on the map, because the underyling mb-source and mb-layers are constantly being removed and readded.

It's unclear how to handle this. While the behavior looks buggy, it is considered accurate since Maps is trying to show the accurate time-based filter.

Should relative time-ranges be ignored when panning/zooming when scaling-type is .mvt?

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[thomasneirynck]

Investigate if mapbox/mapbox-gl-js#8048 would fix this

[thomasneirynck]

After discussion with @nreese.

Will first address the bug of comparing absolute timestamps (which is a consequence of just comparing raw urls iso of the SearchFilters). This will fix most FOUC for time-based data, at the expense of possibly showing some delayed data (due to client-side caching).

Whether previous tiles should actively be discarded (e..g with mapbox/mapbox-gl-js#8048, although not yet available as of 1.12) should be considered a different issue.