encoding/xml: reduce depth limit on wasm

encoding/xml: reduce depth limit on wasm

Wasm can't handle the recusion for XML nested to depth 10,000.
Cut it off at 5,000 instead. This fixes TestCVE202228131 on trybots
in certain conditions.

Also disable TestCVE202230633 to fix 'go test -v encoding/xml' on gomotes.

Also rename errExeceededMaxUnmarshalDepth [misspelled and unwieldy]
to errUnmarshalDepth.

For #56498.

Change-Id: I7cc337ccfee251bfd9771497be0e5272737114f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/446639
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>