Add and use art::GetAndroidRuntimeBinDir.

This method returns the location of the directory containing the
Android Runtime binaries, which is expected to be the Android Runtime
APEX's bin directory on target and the Android Root's bin directory on
host (at least for now).

Also remove art::CommonArtTestImpl::GetTestAndroidRoot as it is no
longer used.

Test: ART gtests on host and target
Bug: 121117762
Change-Id: I4593bbd4d675ca9d3f7b708482aac82c1892a9ad
diff --git a/profman/profile_assistant_test.cc b/profman/profile_assistant_test.cc
index e906151..7b57c46 100644
--- a/profman/profile_assistant_test.cc
+++ b/profman/profile_assistant_test.cc
@@ -198,13 +198,11 @@
   }
 
   std::string GetProfmanCmd() {
-    std::string file_path = GetTestAndroidRoot();
-    file_path += "/bin/profman";
+    std::string file_path = GetAndroidRuntimeBinDir() + "/profman";
     if (kIsDebugBuild) {
       file_path += "d";
     }
-    EXPECT_TRUE(OS::FileExists(file_path.c_str()))
-        << file_path << " should be a valid file path";
+    EXPECT_TRUE(OS::FileExists(file_path.c_str())) << file_path << " should be a valid file path";
     return file_path;
   }