ANDROID: Delete obsolete 16k_gki.fragment.

The correct fragment is the one in build/kernel,
enabled by --page_size or kernel_build.page_size.
This fragment:

- Does not correctly enable incremental FS
- Does not correctly clear LOCALVERSION that
  has 4k for the 4k build.

Bug: 340631213
Bug: 338659380
Change-Id: I31cb004ca639d8ec3dd6201112391c7214971eba
Signed-off-by: Yifan Hong <elsk@google.com>