Revert "androidtest.bash: wait for device to be ready before using it"

Revert "androidtest.bash: wait for device to be ready before using it"

This reverts commit 27b9571de800c05a41081ea80cd934e48e0a8f70.

Reason for revert: broke the multi-device Android builder. And the wait logic is moving to the exec wrapper anyway.

Change-Id: I3e429106bbe70b3a12286f8f229a2b558279eec4
Reviewed-on: https://go-review.googlesource.com/c/163620
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>