[test] Add requires for embedded_stdlib for test that uses the stdlib (#84656)

The test enables the Embedded experimental feature, but beside the
compiler support, it also requires loading the stdlib for embedded, but
the test is not marked as such. For configurations that do not build the
embedded stdlibs, this makes the test fail, because the stdlib is not
available. Mark it with the appropriate requires to avoid this problem.

This should not change the results in the swift.org CI because those CI
configurations build the embedded stdlibs by default.

Author: drodriguez

validation-test/SILOptimizer/rdar161433604.swift

@@ -9,6 +9,7 @@
 // REQUIRES: OS=macosx || OS=linux-gnu
 // REQUIRES: swift_feature_Embedded
 // REQUIRES: swift_feature_LifetimeDependence
+// REQUIRES: embedded_stdlib
 
 struct NoEscapeNoCopy: ~Escapable, ~Copyable {}