Depend on exportable mainline module stubs for doc generation

This change modifies the dependency graph of framework-doc-stubs to
depend on the exportable stub source jar of the mainline modules,
so that the flagged apis symbols are not elided.

Test: m doc dist && unzip -l out/dist/offline-sdk-docs-docs.zip | grep "android/configinfrastructure/aconfig"
Bug: 377585897
Change-Id: I2de643c27417a0ccb21016a3bc495127f3a30f81
diff --git a/api/Android.bp b/api/Android.bp
index 7ef00b0..a98d1d4 100644
--- a/api/Android.bp
+++ b/api/Android.bp
@@ -192,7 +192,7 @@
     cmd: "$(location merge_zips) $(out) $(in)",
     srcs: [
         ":api-stubs-docs-non-updatable{.exportable}",
-        ":all-modules-public-stubs-source",
+        ":all-modules-public-stubs-source-exportable",
     ],
     visibility: ["//visibility:private"], // Used by make module in //development, mind
 }