http2: remove waitTrailers listener after closing a stream

When `writeHear` of `Http2ServerResponse` instance are called with 204,
205 and 304 status codes an underlying stream closes.
If call `end` method after sending any of these status codes it will
cause an error `TypeError: Cannot read property 'Symbol(trailers)' of
undefined` because a reference to `Http2ServerResponse` instance
associated with Http2Stream already was deleted.
The closing of stream causes emitting `watiTrailers` event and, when
this event handles inside `onStreamTrailerReady`  handler, there is
no reference to Http2ServerResponse instance.

Fises: #21740

lib/internal/http2/compat.js

@@ -391,6 +391,8 @@ function onStreamCloseResponse() {
   state.closed = true;
 
   this[kProxySocket] = null;
+
+  this.off('wantTrailers', onStreamTrailersReady);
   this[kResponse] = undefined;
 
   res.emit('finish');

test/parallel/test-http2-compat-serverresponse-end-after-statuses-withou-body.js

@@ -0,0 +1,47 @@
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const h2 = require('http2');
+
+// This test case ensures that calling of res.end after sending
+// 204, 205 and 304 HTTP statuses will not cause an error
+// See issue: https://github.com/nodejs/node/issues/21740
+
+const {
+  HTTP_STATUS_NO_CONTENT,
+  HTTP_STATUS_RESET_CONTENT,
+  HTTP_STATUS_NOT_MODIFIED
+} = h2.constants;
+
+const STATUS_WITHOUT_BODY = [
+  HTTP_STATUS_NO_CONTENT,
+  HTTP_STATUS_RESET_CONTENT,
+  HTTP_STATUS_NOT_MODIFIED,
+];
+const STATUS_CODES_COUNT = STATUS_WITHOUT_BODY.length;
+
+const server = h2.createServer(common.mustCall(function(req, res) {
+  res.writeHead(STATUS_WITHOUT_BODY.pop());
+  res.end();
+}, STATUS_CODES_COUNT));
+
+server.listen(0, common.mustCall(function() {
+  const url = `http://localhost:${server.address().port}`;
+  const client = h2.connect(url, common.mustCall(() => {
+    let responseCount = 0;
+    const closeAfterResponse = () => {
+      if (STATUS_CODES_COUNT === ++responseCount) {
+        client.destroy();
+        server.close();
+      }
+    };
+
+    for (let i = 0; i < STATUS_CODES_COUNT; i++) {
+      const request = client.request();
+      request.on('response', common.mustCall(closeAfterResponse));
+    }
+
+  }));
+}));