health: separate_platform_variant = false

Disable the generation of ndk_platform variant during the
ndk_platform -> ndk migration.

Test: builds
Bug: 177269435
Change-Id: I467eaee53542b152df1d398a8f044eb42fd01772
diff --git a/health/aidl/Android.bp b/health/aidl/Android.bp
index 940e4d8..3a11e64 100644
--- a/health/aidl/Android.bp
+++ b/health/aidl/Android.bp
@@ -26,6 +26,7 @@
             sdk_version: "module_current",
         },
         ndk: {
+            separate_platform_variant: false,
             vndk: {
                 enabled: true,
             },