Revert "ANDROID: vendor_hooks:vendor hook for __alloc_pages_slowpath."

This reverts commit dec2f52d.

The hooks android_vh_alloc_pages_reclaim_bypass and
android_vh_alloc_pages_failure_bypass are not used by any vendor, so
remove it to help with merge issues with future LTS releases.

If this is needed by any real user, it can easily be reverted to add it
back and then the symbol should be added to the abi list at the same
time to prevent it from being removed again later.

Bug: 203756332
Bug: 243629905
Cc: xiaofeng <xiaofeng5@xiaomi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Id313f6971e0b5437fcfc1ed3f8d4c56706217133