Fix the replacing of WCF_N in PHP DDL during app installation

Fix the replacing of WCF_N in PHP DDL during app installation

During app installation the newly installed app might not yet be stored within
the application cache, thus failing to replace the `1` within the table
structure definition.

Fix this by setting the `skipCache` parameter to `true`. This will increase the
number of database queries, because applications will be checked once for each
defined table and for each defined FOREIGN KEY, but I don't see a simple fix
for this issue that avoids this increase in query count. Specifically we cannot
simply reset the application cache after inserting the application into
wcf1_application.