Compile `ArtServiceTests` for both architectures (where applicable).

This is to allow this test to also run on 32-bit devices.

Test: Run `v2/android-virtual-infra/test_mapping/presubmit-avd` against
      `cf_x86_tv-userdebug`
Bug: 259113805
Ignore-AOSP-First: ART Services
Change-Id: Icf765e08d6cb947791d137e817c66a6ef651f49f
diff --git a/libartservice/service/Android.bp b/libartservice/service/Android.bp
index 55653b5..92ad57c 100644
--- a/libartservice/service/Android.bp
+++ b/libartservice/service/Android.bp
@@ -205,6 +205,7 @@
         "libdexmakerjvmtiagent",
         "libstaticjvmtiagent",
     ],
+    compile_multilib: "both",
 
     // TODO: This module should move to sdk_version: "system_server_current" when possible,
     //   as this will restrict the APIs available to just that expected system API. For now,