Remove 3rd party lua plugin support (#11821)

internal/ingress/controller/template/configmap.go

@@ -67,7 +67,6 @@ const (
 	globalAuthCacheDuration       = "global-auth-cache-duration"
 	globalAuthAlwaysSetCookie     = "global-auth-always-set-cookie"
 	luaSharedDictsKey             = "lua-shared-dicts"
-	plugins                       = "plugins"
 	debugConnections              = "debug-connections"
 	workerSerialReloads           = "enable-serial-reloads"
 )
@@ -416,11 +415,6 @@ func ReadConfig(src map[string]string) config.Configuration {
 		delete(conf, workerSerialReloads)
 	}
 
-	if val, ok := conf[plugins]; ok {
-		to.Plugins = splitAndTrimSpace(val, ",")
-		delete(conf, plugins)
-	}
-
 	if val, ok := conf[debugConnections]; ok {
 		delete(conf, debugConnections)
 		for _, i := range splitAndTrimSpace(val, ",") {