Bug 18121: Replace opac_news.new with opac_news.content in notices templates

Bug 18121: Replace opac_news.new with opac_news.content in notices templates

Bug 17960 replaces opac_news.new with opac_news.content, we can replace
the content of the notices' templates automatically.

Test plan:
Checkout a commit prior to bug 17960. Install a new DB with sample data.
You should have notices with <<opac_news.new>>

Switch to a branch with this patch, on top of master

Execute the updatedatabase.pl sript
=> The notices with opac_news.new should have been replaced with
opac_news.content

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>