[iOS] Fix BWG UI Bugs

- Ensures the IPH shows after the BWG promo flow is dismissed by
ignoring the FET component in bubble presenter. We still use the
bubble presenter instead of creating a custom bubble popup to ensure
we still abide by UI behaviors taken care of from bubble presenter.
- Ensures the IPH doesn't show when the promo is shown from the omnibox
- Fixes a pref crash from a pref that was moved from a local to profile
pref.

Fixed: 430271992, 433467893
Change-Id: Id01d400a6fb6aee4444e2b108b1f621c0428e525
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6777358
Reviewed-by: Nicolas MacBeth <nicolasmacbeth@google.com>
Reviewed-by: Adam Arcaro <adamta@google.com>
Auto-Submit: Joemer Ramos <joemerramos@google.com>
Commit-Queue: Adam Arcaro <adamta@google.com>
Cr-Commit-Position: refs/heads/main@{#1490273}