Bug 1683551: Remove duplicate headings for About / T&C / Privacy pages

This patch is only for newly installed sites ONLY
- existing sites will need to edit via Admin -> Static pages

behatnotneeded

Change-Id: I44495c985bce200656d1b80c6458331d888bc666
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
(cherry picked from commit efc7dc03)