flags: remove enable-omnibox-voice-search-always-visible

This change:
1) Removes this flag
2) Removes the backing feature OmniboxVoiceSearchAlwaysVisible
3) Reworks some of the Java location bar layout tests that used to
   depend on the feature

Bug: 807726
Change-Id: Iced90b4ca7828a8ac7f92630579fb88ff1c87f7c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1531033
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Auto-Submit: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#643393}
9 files changed