async_hooks: remove runtime deprecation

As part of the backport to 8.x, this change removes the runtime
deprecation making this a docs-only deprecation for 8.x.

PR-URL: #19517
Reviewed-By: mcollina - Matteo Collina <matteo.collina@gmail.com>

lib/async_hooks.js

@@ -143,17 +143,6 @@ function triggerAsyncId() {
 
 const destroyedSymbol = Symbol('destroyed');
 
-let emitBeforeAfterWarning = true;
-function showEmitBeforeAfterWarning() {
-  if (emitBeforeAfterWarning) {
-    process.emitWarning(
-      'asyncResource.emitBefore and emitAfter are deprecated. Please use ' +
-      'asyncResource.runInAsyncScope instead',
-      'DeprecationWarning', 'DEP0098');
-    emitBeforeAfterWarning = false;
-  }
-}
-
 class AsyncResource {
   constructor(type, opts = {}) {
     if (typeof type !== 'string')
@@ -189,13 +178,11 @@ class AsyncResource {
   }
 
   emitBefore() {
-    showEmitBeforeAfterWarning();
     emitBefore(this[async_id_symbol], this[trigger_async_id_symbol]);
     return this;
   }
 
   emitAfter() {
-    showEmitBeforeAfterWarning();
     emitAfter(this[async_id_symbol]);
     return this;
   }