Update default value of EXTRA_PREFER_NEW in ChromeTabbedActivity

Default to creating a new instance when FLAG_ACTIVITY_MULTIPLE_TASK is
set. This is required to fulfill new window creation requests from the
OS.

Bug: 436477060
Change-Id: I53dd68d6eef4b1ce3bf3991fecaff2cf32fd171d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6824467
Reviewed-by: Sirisha Kavuluru <skavuluru@google.com>
Commit-Queue: Aishwarya Rajesh <aishwaryarj@google.com>
Cr-Commit-Position: refs/heads/main@{#1499702}