[mod] google engine: reduce mobile UI parameters to what is needed

Reverse engineering shows that not all of the parameters used by google's mobile
UI (aka "more results" button) are needed [1].

[1] https://github.com/searxng/searxng/pull/160#issuecomment-865013625



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>