New J2K: do not find import usages in AST building phase

It is a rather heavy operation and it increases conversion time
Related to #KT-31848

nj2k/testData/newJ2k/function/java8MRKFunctionExpectedType.kt

@@ -77,7 +77,7 @@ internal class Java8Class {
     }
 
     fun testGenericFunctions() {
-        val emptyList: Function0<kotlin.collections.List<String>> = { emptyList() }
+        val emptyList: Function0<List<String>> = { emptyList() }
         val list = emptyList.invoke()
         list[0]
     }

nj2k/testData/newJ2k/function/java8MRSamConstructor.kt

@@ -122,10 +122,10 @@ internal class Java8Class {
     }
 
     fun testGenericFunctions() {
-        val emptyList: JFunction1<kotlin.collections.List<String>> = JFunction1 { emptyList() }
+        val emptyList: JFunction1<List<String>> = JFunction1 { emptyList() }
         emptyList.foo()
-        MethodReferenceHelperClass.staticFun1(JFunction1<kotlin.collections.List<String>> { emptyList() })
-        h.memberFun1(JFunction1<kotlin.collections.List<String>> { emptyList() })
+        MethodReferenceHelperClass.staticFun1(JFunction1<List<String>> { emptyList() })
+        h.memberFun1(JFunction1<List<String>> { emptyList() })
     }
 
     fun memberFun(): Int {