Expand @FlaggedApi(Flags.FLAG) in *all* API signature files

A previous CL added the auto-generated aconfig Flags.FLAG sources to
metalava's input when generating core/api/current.txt, so metalava would
expand the Flags.FLAG to their values.

Do the same for the build targets for the other (system, module-lib,
test) API signature files in core/api.

Also update the API signature files accordingly.

Bug: 301859633
Test: m checkapi
Change-Id: Id06d77e897ecfddeaa42f75cba4d6d37bee9d1b1
diff --git a/api/StubLibraries.bp b/api/StubLibraries.bp
index 56a69b4..e5e0ad3 100644
--- a/api/StubLibraries.bp
+++ b/api/StubLibraries.bp
@@ -86,6 +86,9 @@
 
 droidstubs {
     name: "system-api-stubs-docs-non-updatable",
+    srcs: [
+        ":framework-minus-apex-aconfig-srcjars",
+    ],
     defaults: [
         "android-non-updatable-stubs-defaults",
         "module-classpath-stubs-defaults",
@@ -126,6 +129,9 @@
 
 droidstubs {
     name: "test-api-stubs-docs-non-updatable",
+    srcs: [
+        ":framework-minus-apex-aconfig-srcjars",
+    ],
     defaults: [
         "android-non-updatable-stubs-defaults",
         "module-classpath-stubs-defaults",
@@ -173,6 +179,9 @@
 
 droidstubs {
     name: "module-lib-api-stubs-docs-non-updatable",
+    srcs: [
+        ":framework-minus-apex-aconfig-srcjars",
+    ],
     defaults: [
         "android-non-updatable-stubs-defaults",
         "module-classpath-stubs-defaults",