java completion: remove irrelevant suggestions after Unresolved:: (IDEA-201798)

to enable chain completion, which only works when there are no other suggestions

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/completion/normal/ChainedMethodReferenceWithNoPrefix.java

@@ -0,0 +1,5 @@
+class A {
+  {
+    Runnable r = Strings::<caret>
+  }
+}