Suppress IME show-up on search mode.

- call SearchView#clearFocus()
- prepare the search view on onCreate()

Though SearchView itself tries to suppress IME on its clearFocus(),
ondemand SearchView creation forces IME show-up for some reason
(attaching it to ActionBar might be the cause of the harm).

Just creating the view every time on onCreate() avoids the problem.
It doesn't hurt performance or any other app capability much.

This change also removes some stale code for showing up IME, which
is needless anyway.

Bug: 5104943
Change-Id: I4c542b3d0cdc5287c9285493e8e5ed0ce25cb204