[iOS] Conditionally pass Profile to SendTabPushNotificationClient tests

This change updates the SendTabPushNotificationClient constructor in
unit tests to conditionally accept a ProfileIOS based on
IsMultiProfilePushNotificationHandlingEnabled().

This ensures unit tests run correctly regardless of the feature's state,
preparing the test suite for when multi-profile push handling is
enabled.

Bug: 379077722
Change-Id: I08b7850ee28975deac2b81d59d04c8098765183e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6617120
Auto-Submit: Benjamin Williams <bwwilliams@google.com>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Benjamin Williams <bwwilliams@google.com>
Cr-Commit-Position: refs/heads/main@{#1468666}