file_manager: inline util::IsNonNativeFileSystemType

BUG=None
TEST=manual

Change-Id: I146762eeb3977c876036a370b46062b6c8a41134
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4562689


Reviewed-by: Melissa Zhang <melzhang@chromium.org>
Auto-Submit: Nigel Tao <nigeltao@chromium.org>
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Commit-Queue: Melissa Zhang <melzhang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1148941}