Fix crash on AppInfo screen

We start a search page with a request code which is same as
"uninstall" request code. The root cause is we handle same
reuqest code for different event.

We redefine an unique request code for "search" feature.

Fixes: 124775813
Test: Click search and back to App info screen.
Change-Id: I8ab21c30b605bcb65b6d4bd9fceb749a65a49f80