[JS IR BE] Disable @library test for JS IR

@library is an internal annotation used in legacy stdlib to expose
declarations written in JS.

IR BE based stdlib will not include JS code thus annotation will not
be supported.

js/js.translator/testData/box/native/library.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS_IR
+// DONT_TARGET_EXACT_BACKEND: JS_IR
 // EXPECTED_REACHABLE_NODES: 1282
 @file:Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER")
 package foo