Fix bad pathing creating double-slashes.

[Camwyn]

To do so we run array_filter() (without a second param - so it just removes empty items) on $path before we run implode().

When we implode the $path arrays, ensure we first remove all empty items or we wind up with things like /site/tec/dev/themes/twentytwenty//tribe/events-pro//custom-tables-v1 instead of /site/tec/dev/themes/twentytwenty/tribe/events-pro/custom-tables-v1

:movie_camera: https://d.pr/v/ihcOLc

Part of ECP-1400

Related: https://github.com/the-events-calendar/events-pro/pull/2139