Don't try to deserialize PaintRecords when security constrained

This is similar to the logic for reading PaintImage, where we enforce
the same rules. Prevents nullptr deref when trying to access the
transfer_cache.

This also makes the comment in paint_op_reader.h actually true:

> 1) PaintRecords ... are ignored.
> ...
> If set to true, the above constraints are validated during
> deserialization and the data types specified above are ignored.

Bug: chromium:327827229
Change-Id: Ie881c901f72f9ad2c37bca461579bbfee5b9d47d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5380552
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
Cr-Commit-Position: refs/heads/main@{#1275656}