Use node:16.5 for frontend instead of node:16 (#16591)

Use node:16.5 for frontend  instead of node:16 (#16591)

* Disable frontend testing

Jest does not appear to work on the latest node 16.6.0 and fails with an inscrutable
message.

I have been unable to work out what the problem is. This PR simply disables the
test-frontend part in the makefile.

Another alternative would be to drop node to node 14 - which is the LTS for node.

Signed-off-by: Andrew Thornton <art27@cantab.net>
* actually just tell on 16.5 instead

Signed-off-by: Andrew Thornton <art27@cantab.net>
* Use node 16.5 instead of 16

Signed-off-by: Andrew Thornton <art27@cantab.net>