Ash: Update comment for disabled NavigateGroupings test

The SwitchAccessTest.NavigateGroupings browser test is disabled on MSAN
builds due to a renderer process crash.

This change updates the comment for the disabled test to include more
specific details from the MSAN stack trace. The crash is caused by a
use-of-uninitialized-value error within
blink::CSSParserImpl::ParseStyleSheet during the parsing of default
stylesheets. A separate bug is then filed to specifically track the
blink issue. https://crbug.com/431933537

This additional context clarifies that the root cause is an underlying
Blink issue and will aid future investigation.

is_debug=false, target_os="chromeos", symbol_level=2. Then symbolize the
report with asan_symbolize.py.

Bug: b:281717553, 388867933, 431933537
Test: Run SwitchAccessTest.NavigateGroupings with is_msan=true,
Change-Id: I0003e572787dcbdcc5c4668c3b2ca93e95c6d0c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6731412
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Di Wu <diwux@google.com>
Cr-Commit-Position: refs/heads/main@{#1486778}