[iOS] Remove HistoryOptInPrimaryButtonMatcher()

Function replaced by SigninScreenPromoPrimaryButtonMatcher()

Related to:
* crrev.com/c/4976172 Create SigninScreenPromoPrimaryButtonMatcher
* crrev.com/i/6599776 Cleanup in ios_internal
> crrev.com/c/4979746 Remove HistoryOptInPrimaryButtonMatcher

Change-Id: I98375d1c68f1092283c27d74dbf0335487cad91e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4979746
Commit-Queue: Tanmoy Mollik <triploblastic@google.com>
Auto-Submit: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Tanmoy Mollik <triploblastic@google.com>
Cr-Commit-Position: refs/heads/main@{#1216956}