binderStabilityIntegrationTest: product support

This test was added this year, but I did not add 'product'. Without
this, any service registered from 'product' would fail.

Bug: 385355208
Test: atest binderStabilityIntegrationTest
Change-Id: I418cdfc5051933566cd7d06ed0a9f5d88b7ce660

Author: Steven Moreland

libs/binder/tests/binderStabilityIntegrationTest.cpp

@@ -47,6 +47,7 @@ TEST_P(BinderStabilityIntegrationTest, ExpectedStabilityForItsPartition) {
 
     Stability::Level level = Stability::Level::UNDECLARED;
     switch (partition) {
+        case Partition::PRODUCT:
         case Partition::SYSTEM:
         case Partition::SYSTEM_EXT:
             level = Stability::Level::SYSTEM;