remove flash codegen (#16372)

Author: wing328

modules/openapi-generator/src/main/java/org/openapitools/codegen/GeneratorLanguage.java

@@ -26,7 +26,7 @@ public enum GeneratorLanguage {
     JAVA("Java"), ADA("Ada"), APEX("Apex"), BASH("Bash"), C("C"),
     CLOJURE("Clojure"), C_PLUS_PLUS("C++"), CRYSTAL("Crystal"), C_SHARP("C#"),
     DART("Dart"), EIFFEL("Eiffel"), ELIXIR("Elixir"), ELM("Elm"),
-    ERLANG("Erlang"), FLASH("Flash"), F_SHARP("F#"), GO("Go"),
+    ERLANG("Erlang"), F_SHARP("F#"), GO("Go"),
     JAVASCRIPT("Javascript"), GRAPH_QL("GraphQL"), GROOVY("Groovy"),
     HASKELL("Haskell"), HTTP("Jetbrains HTTP Client (HTTP/REST)"), TYPESCRIPT("Typescript"), K_SIX("k6"), KOTLIN("Kotlin"),
     KTORM("Ktorm"), LUA("Lua"), MYSQL("Mysql"), NIM("Nim"),