Convert ActionLookupKey implementations to directly implement SkyKey, removing the layer of indirection of getting SkyKey out of ActionLookupKey, which uses more memory for no reason.

PiperOrigin-RevId: 181658615
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
index e0bb1f7..3846003 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
@@ -1182,7 +1182,10 @@
     PathFragment execPath = PathFragment.create("out").getRelative(name);
     Path path = execRoot.getRelative(execPath);
     return new SpecialArtifact(
-        path, Root.asDerivedRoot(execRoot, execRoot.getRelative("out")), execPath, ALL_OWNER,
+        path,
+        Root.asDerivedRoot(execRoot, execRoot.getRelative("out")),
+        execPath,
+        ACTION_LOOKUP_KEY,
         SpecialArtifactType.TREE);
   }