BACKPORT: f2fs: kill heap-based allocation

No one uses this feature. Let's kill it.

Reviewed-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Bug: 361829529
Bug: 381105141
(cherry picked from commit 4e0197f9)
Signed-off-by: Daeho Jeong <daehojeong@google.com>
(cherry picked from https://android-review.googlesource.com/q/commit:acc7335e1f45e3f619e3784c2affc6f6491c2049)
Merged-In: I3bd733b0535d4c18f0eb8eb1a8692fb31462e2c8
Change-Id: I3bd733b0535d4c18f0eb8eb1a8692fb31462e2c8