af-alg: Remove plugin for deprecated AF_ALG interface

The 7.2 kernel has officially deprecated the interface and it will soon
be removed (support for hardware crypto offload has already been removed).

Also removed the corresponding test scenarios.

testing/scripts/recipes/013_strongswan.mk

@@ -82,7 +82,6 @@ CONFIG_OPTS = \
 	--enable-hmac \
 	--enable-chapoly \
 	--enable-ha \
-	--enable-af-alg \
 	--enable-whitelist \
 	--enable-xauth-generic \
 	--enable-xauth-eap \