[cxx-interop] Cleanup a test now that we can import constructors (#34460)

Author: hlopko

test/Interop/Cxx/static/Inputs/static-var.h

@@ -24,7 +24,6 @@ static constexpr int staticConstexpr = makeStaticConstexpr();
 
 class NonTrivial {
 public:
-  explicit NonTrivial() : val(-1) {}
   explicit NonTrivial(int val) : val(val) {}
   constexpr NonTrivial(int val, int val2) : val(val + val2) {}
   int val;

test/Interop/Cxx/static/static-var.swift

@@ -67,10 +67,7 @@ StaticVarTestSuite.test("static-non-trivial-write-from-cxx") {
 
 StaticVarTestSuite.test("static-non-trivial-write-from-swift") {
   expectNotEqual(1026, staticNonTrivial.val)
-  //TODO: Delete `NonTrivial()` adn use `NonTrivial(int)` constructor once
-  // apple/swift/pull/30630 is merged.
-  staticNonTrivial = NonTrivial()
-  staticNonTrivial.val = 1026
+  staticNonTrivial = NonTrivial(1026)
   expectEqual(1026, getstaticNonTrivialFromCxx().pointee.val)
 }