[Accessibility] remove additional role setting for column header

Currently, While navigating in table row cells in sortable column,
column header text is not associated with cell content.

The root cause is that we set the role for column header to be button
if it's sortable, which causing screen reader won't identify the
associated column header of the cell. With the extra text 'Press enter
to apply sorting filter', users have enough information to interact
with column header. Thus, remove this line to allow column header text
associated with cell content. Now using 'ctrl+shift+alt+up' key on cell,
screen reader will announce its column header info even if it's in
sortable column.

Bug: none
Change-Id: Ib4a2f683a0d15e241887f9bcfbc03ad4434bf067
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/4559346
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
Commit-Queue: Yanling Wang <yanlingwang@microsoft.com>
diff --git a/front_end/ui/components/data_grid/DataGrid.ts b/front_end/ui/components/data_grid/DataGrid.ts
index f5a857a..7204197 100644
--- a/front_end/ui/components/data_grid/DataGrid.ts
+++ b/front_end/ui/components/data_grid/DataGrid.ts
@@ -811,7 +811,6 @@
                   }}
                   title=${col.title}
                   aria-sort=${LitHtml.Directives.ifDefined(this.#ariaSortForHeader(col))}
-                  role=${col.sortable ? 'button' : 'columnheader'}
                   aria-colindex=${columnIndex + 1}
                   data-row-index='0'
                   data-col-index=${columnIndex}