tests: stop updating the search engine

tests: stop updating the search engine

While running includes/api tests, profiling reports tests are doing
hundred of inserts followed by hundred of matching deletes. That is due
to the search engine updates.

For almost all tests, there is no need to update the search engine, that
is a waste of I/O and CPU cycles.

Speed up the run by using 'SearchEngineDummy'.

Our search tests still pass since they take care of setting up a search
engine.

Change-Id: Ic10e989e27fd3901ea215f544a0490baef57f0a4