[iOS][Toolbar] Remove secondaryToolbarCoordinator refs from BVC

Remove checks of SecondaryToolbarCoordinator as it's always initialized:
https://source.chromium.org/chromium/chromium/src/+/main:ios/chrome/browser/ui/browser_view/browser_coordinator.mm;l=769;drc=4764a9af525eb819410d7aa129021578a8bf799f

and started:
https://source.chromium.org/chromium/chromium/src/+/main:ios/chrome/browser/ui/browser_view/browser_view_controller.mm;l=1421;drc=24de59c47af50ef975186f740c578f5ed39fea97

Bug: 1449960
Change-Id: I3e25009c69685bf59e16b01f1e55f62d38bc7638
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4575205
Reviewed-by: Federica Germinario <fedegermi@google.com>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1151931}