Remove obsolete droidstub args

- I see no usages of private_api_filename / private.txt /
  private_dex_api_filename
- tags are no longer used as of
  Iff355041d88eb59ac47dd19a03e993cf1ce3927e
- api_filename/removed_api_filename does nothing if check_api is
  specified. test-api does not need a removed.txt

Bug: 152479829
Bug: 144149403
Test: m
Change-Id: Ic1e859dc6aa91f8d7b4f285b63d3faafb27edc9b

StubLibraries.bp

@@ -97,9 +97,6 @@ stubs_defaults {
 droidstubs {
     name: "api-stubs-docs",
     defaults: ["metalava-full-api-stubs-default"],
-    api_filename: "public_api.txt",
-    private_api_filename: "private.txt",
-    removed_api_filename: "removed.txt",
     removed_dex_api_filename: "removed-dex.txt",
     arg_files: [
         "core/res/AndroidManifest.xml",
@@ -142,10 +139,6 @@ module_libs = " " +
 droidstubs {
     name: "system-api-stubs-docs",
     defaults: ["metalava-full-api-stubs-default"],
-    api_tag_name: "SYSTEM",
-    api_filename: "system-api.txt",
-    private_api_filename: "system-private.txt",
-    removed_api_filename: "system-removed.txt",
     removed_dex_api_filename: "system-removed-dex.txt",
     arg_files: [
         "core/res/AndroidManifest.xml",
@@ -178,9 +171,6 @@ droidstubs {
 droidstubs {
     name: "test-api-stubs-docs",
     defaults: ["metalava-full-api-stubs-default"],
-    api_tag_name: "TEST",
-    api_filename: "test-api.txt",
-    removed_api_filename: "test-removed.txt",
     arg_files: [
         "core/res/AndroidManifest.xml",
     ],
@@ -216,7 +206,6 @@ droidstubs {
 droidstubs {
     name: "module-lib-api",
     defaults: ["metalava-full-api-stubs-default"],
-    api_tag_name: "MODULE_LIB",
     arg_files: ["core/res/AndroidManifest.xml"],
     args: metalava_framework_docs_args + module_libs,
     check_api: {