Update ENABLE_EXTENSIONS build flag in ChromeBrowsingDataRemoverDelegate

Now that we have extensions on desktop Android, there's a new build flag
for extensions ENABLE_EXTENSIONS_CORE required for "traditional
extensions platforms + desktop Android". Switch to that. This enables
clearing extension activity log data on desktop Android, as we do on
Win/Mac/Linux/Chrome OS.

See bug for details on the history of the two build flags.

Bug: 494643383
Change-Id: I5152cfbbbe1ba20fca82f58182180c1b97caadef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7690060
Reviewed-by: Martin Šrámek <msramek@chromium.org>
Auto-Submit: James Cook <jamescook@chromium.org>
Commit-Queue: Martin Šrámek <msramek@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1604551}