get bucket from the image, don't do a string replace on domains for video thumbs

(cherry picked from commit ada810dc56a9816cf369f0ece2cf3c0d8313f266)
Add support for replace query param

Add support for ?replace=true query param. This will force the
thumbnailer to replace the cached (disk) version of the thumbnail

(cherry picked from commit 869a90902cbfcdc4c27a88a483219224ddbca599)
Set replaceThumbnail to false by default.

/cc @nmonterroso

(cherry picked from commit c34ebc9973412ad0f7de6aaa25db5d7f9881efbb)