[Tests] InitAccessors/NFC: All init accessor tests require "asserts"

Because the feature is experimental and the flag would not be present
in the production compilers.

Author: xedin

test/SILOptimizer/init_accessor_raw_sil_lowering.swift

@@ -1,5 +1,7 @@
 // RUN: %target-swift-frontend -enable-experimental-feature InitAccessors -Xllvm -sil-print-after=definite-init -emit-sil %s -o /dev/null 2>&1 | %FileCheck %s
 
+// REQUIRES: asserts
+
 struct Test1 {
   var _a: Int
   var _b: String

test/decl/var/init_accessors.swift

@@ -1,5 +1,7 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-feature InitAccessors
 
+// REQUIRES: asserts
+
 func test_empty_init_accessor() {
   struct Test {
     var empty: Int {