Fix ResetColumnHeight() for NG multicol.

CL:3569752 didn't go far enough. We could also end up in
MultiColumnFragmentainerGroup::ResetColumnHeight() from
LayoutMultiColumnSet::AppendNewFragmentainerGroup() as well.

Fix ResetColumnHeight() to handle NG instead of special-functions for
NG, and skip the legacy parts. The most problematic part about
ResetColumnHeight() was the call to EnclosingFragmentationContext(),
which ends up in LayoutFlowThread::LocateFlowThreadContainingBlockOf(),
which just doesn't behave with NG in nested multicol situations (we'll
recognize a flow thread object as a legacy object among NG objects, and
therefore refuse to walk up any further). There's a special hack for
legends there that bypasses this, which will cause us to set a column
height, and upset SetColumnBlockSizeFromNG() later on. Let's just not
go there.

This also fixes another virtual/layout_ng_printing/ test.

Bug: 1308024
Change-Id: Iaa5a36ac099b618b5ab0173d19e47a65ec96d73a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3571864
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/main@{#989625}