Add default encryption algorithms to SPs in the fallback aggregate

This commit adds the default AES128-CBC encryption algorithm to
SPs that do not have any registered block encryption algorithms.
Previous commits add them to the test and production aggregates;
this commit is the last step in rolling the defaults out.

See ukf/ukf-meta#243 for details

mdx/uk/generate.xml

@@ -600,6 +600,7 @@
                 <bean parent="mda.SetCacheDurationStage"
                     p:cacheDuration="${cacheDuration.aggregate.duration}"/>
                 <ref bean="stripEntityScopes"/>
+                <ref bean="uk_add_cbc_encryption"/>
                 <ref bean="stripEmptyExtensions"/>
                 <ref bean="uk_finaliseFallback"/>
                 <ref bean="uk_normaliseFallback"/>