[stdlib][test] Remove problematic else branches in availability checks

Testing the old behaviour can cause issues when the new availability
gets properly defined. Just check the new behaviour, which is what we
are doing in other stdlib tests.

test/stdlib/BridgedObjectDebuggerSupport.swift

@@ -80,8 +80,6 @@ StringForPrintObjectTests.test("NSStringUTF8") {
 
   if #available(SwiftStdlib 6.1, *) {
     expectEqual("🏂☃❅❆❄︎⛄️❄️\n", printed)
-  } else {
-    expectEqual("\"🏂☃❅❆❄︎⛄️❄️\"\n", printed)
   }
 
   expectEqual(printed, debug)

test/stdlib/DebuggerSupport.swift

@@ -106,11 +106,6 @@ if #available(SwiftStdlib 6.1, *) {
     let printed = _stringForPrintObject("hello\nworld")
     expectEqual(printed, "hello\nworld\n")
   }
-} else {
-  StringForPrintObjectTests.test("String") {
-    let printed = _stringForPrintObject("hello\nworld")
-    expectEqual(printed, "\"hello\\nworld\"\n")
-  }
 }
 
 class RefCountedObj {