etherpad - use ssl_ciphersuite

In the past, when we changed SSL cipher settings
we had to create many changes, usually one per service.

Then Giuseppe introduced ssl_ciphersuite in I9bc1104b7f770d9
which moves the settings into a centralized function.

This change makes it actually use the new function.

One last time we are going through all of the services,
but in the future we will be able make a single change
to update ciphers across misc. services.

Change-Id: Id35d5235d2ac3141984f3fa6e5991f15c4f00030
Merge "etherpad - use ssl_ciphersuite" into production