media: deprecate mediacodec feature flag aconfig

These used a more redundant namespace than desired.

Bug: 297920102
Change-Id: Id04d81f9b45362ca216ce9f2713efb39cd91c5f2
diff --git a/media/aconfig/Android.bp b/media/aconfig/Android.bp
index f95d723..31bb431 100644
--- a/media/aconfig/Android.bp
+++ b/media/aconfig/Android.bp
@@ -1,15 +1,18 @@
+// deprecated
 aconfig_declarations {
     name: "aconfig_mediacodec_flags",
     package: "com.android.media.codec.flags",
     srcs: ["mediacodec_flags.aconfig"],
 }
 
+// deprecated
 java_aconfig_library {
     name: "aconfig_mediacodec_flags_java_lib",
     aconfig_declarations: "aconfig_mediacodec_flags",
     defaults: ["framework-minus-apex-aconfig-java-defaults"],
 }
 
+// deprecated
 cc_aconfig_library {
     name: "aconfig_mediacodec_flags_c_lib",
     min_sdk_version: "30",
diff --git a/media/aconfig/mediacodec_flags.aconfig b/media/aconfig/mediacodec_flags.aconfig
index c82ad4d..be0fc5c 100644
--- a/media/aconfig/mediacodec_flags.aconfig
+++ b/media/aconfig/mediacodec_flags.aconfig
@@ -1,5 +1,10 @@
 package: "com.android.media.codec.flags"
 
+# ******************************************************************
+#            !!! DO NOT ADD FURTHER FLAGS TO THIS FILE !!!
+#            !!!     USE codec_fwk.aconfig INSTEAD     !!!
+# ******************************************************************
+
 flag {
   name: "large_audio_frame"
   namespace: "codec_fwk"