Remove ability to delete annot in CJS_Document::removeField()

This path has only been present under XFA, and has resulted in
several bugs, including the referenced one. There is a breakage in some
XFA functionality, but I'm not confident we can do this without
re-engineering all of fpdfsdk widget ownership.

Bug: 891210
Change-Id: I5aa158fa5359b1c8338046eefb25fb25df9ace48
Reviewed-on: https://pdfium-review.googlesource.com/c/43311
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

testing/resources/javascript/xfa_specific/resolve_nodes_1_expected.txt

diff --git a/testing/resources/javascript/xfa_specific/resolve_nodes_1_expected.txt b/testing/resources/javascript/xfa_specific/resolve_nodes_1_expected.txt
index d4cc442..335a4e2 100644
--- a/testing/resources/javascript/xfa_specific/resolve_nodes_1_expected.txt
+++ b/testing/resources/javascript/xfa_specific/resolve_nodes_1_expected.txt
@@ -1 +1 @@
-: \Find 1 items
+: Find 12 items