ART: Disable app images for test 912

To have precise info for actually loaded classes.

Bug: 31684578
Test: m ART_TEST_INTERPRETER=true test-art-host-run-test-912-classes
Change-Id: I06a9303befab40c619f9d1e3d677024c8f3b0ba3
diff --git a/test/912-classes/run b/test/912-classes/run
index 4379349..20dfc4b 100755
--- a/test/912-classes/run
+++ b/test/912-classes/run
@@ -14,6 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# This test checks which classes are initiated by a classloader. App images preload classes.
+# In certain configurations, the app images may be valid even in a new classloader. Turn off
+# app images to avoid the issue.
+
 ./default-run "$@" --experimental agents \
                    --experimental runtime-plugins \
-                   --jvmti
+                   --jvmti \
+                   --no-app-image