Remove test that is incompatible with laziness

Going through sil-opt is going to print the contents of the module
without forcing the attribute which renders the test toothless. Now that
we have the multifile test, we're testing it can be round-tripped
through serialization anyhow.

Author: CodaFi

test/Serialization/serialize_attr.swift

@@ -82,15 +82,3 @@ public class CC<T : PP> {
 // CHECK-DAG: sil [serialized] [_specialize exported: false, kind: full, where T == Int, U == Float] [canonical] [ossa] @$s14serialize_attr14specializeThis_1uyx_q_tr0_lF : $@convention(thin) <T, U> (@in_guaranteed T, @in_guaranteed U) -> () {
 
 // CHECK-DAG: sil [serialized] [noinline] [_specialize exported: false, kind: full, where T == RR, U == SS] [canonical] [ossa] @$s14serialize_attr2CCC3foo_1gqd___AA2GGVyxGtqd___AHtAA2QQRd__lF : $@convention(method) <T where T : PP><U where U : QQ> (@in_guaranteed U, GG<T>, @guaranteed CC<T>) -> (@out U, GG<T>) {
-
-
- // @_typeEraser
- // -----------------------------------------------------------------------------
-
-public class AnyP: P {
-  public init<T: P>(erasing: T) {}
-}
-
-// CHECK-DAG: @_typeEraser(AnyP) protocol P
-@_typeEraser(AnyP)
-public protocol P {}