Enable android-support-multidex for unbundled branches

bg: healthfitness is mainline module (unbundled) our tests depend on
"hilt_android_testing" which depends on "android-support-multidex"

problem: for the test coverage we need to build test + code unbundled so
we need to enable "android-support-multidex" to run on unbundled
branches

Bug: 278203429
Test: Test: DIST_DIR=dist_dir TARGET_BUILD_VARIANT=userdebug PRODUCT=mainline_modules_x86 COVERAGE_MODULES="healthfitness" ./vendor/google/build/build_unbundled_coverage_mainline_module.sh
Change-Id: I34dfb8901c549d821ae47aa2e4c1953f83e5514f
diff --git a/library/Android.bp b/library/Android.bp
index 467761a..1189c23 100644
--- a/library/Android.bp
+++ b/library/Android.bp
@@ -28,10 +28,4 @@
     srcs: [
         "src/**/*.java",
     ],
-    product_variables: {
-        unbundled_build: {
-            // Don't build the library in unbundled branches.
-            enabled: false,
-        },
-    },
 }