[IMP] web: list view grouped layout is nicer

Task ID: 1860033

When the list view is grouped,
Before this commit the group title took as much space in the group
content as the first column of the table, and the space under this title
was not usable by the content (it was blank)

After this commit, the group title takes as much space as the sum of the
selector, sequence and first content column, but the space in the group
content under the title is used, so there is less wasted white space.