http2: upload improvements

Make send buffer smaller to have progress and "upload done" reporting
closer to reality. Fix handling of send "drain" condition to no longer
trigger once the transfer loop reports it is done sending. Also do not
trigger the send "drain" on RST streams.

Background:
- a upload stall was reported in #11157 that timed out
- test_07_33a reproduces a problem with such a stall if the
  server 404s the request and RSTs the stream.
- test_07_33b verifies a successful PUT, using the parameters
  from #11157 and checks success

Ref: #11157
Closes #11165

tests/http/test_07_upload.py

@@ -240,7 +240,50 @@ class TestUpload:
         url = f'https://{env.authority_for(env.domain1, proto)}/curltest/put?id=[0-{count-1}]'
         r = curl.http_put(urls=[url], fdata=fdata, alpn_proto=proto)
         r.check_response(count=count, http_status=200)
-        r.check_response(count=count, http_status=200)
+
+    # issue #11157, upload that is 404'ed by server, needs to terminate
+    # correctly and not time out on sending
+    def test_07_33_issue_11157a(self, env: Env, httpd, nghttpx, repeat):
+        proto = 'h2'
+        fdata = os.path.join(env.gen_dir, 'data-10m')
+        # send a POST to our PUT handler which will send immediately a 404 back
+        url = f'https://{env.authority_for(env.domain1, proto)}/curltest/put'
+        curl = CurlClient(env=env)
+        r = curl.run_direct(with_stats=True, args=[
+            '--resolve', f'{env.authority_for(env.domain1, proto)}:127.0.0.1',
+            '--cacert', env.ca.cert_file,
+            '--request', 'POST',
+            '--max-time', '5', '-v',
+            '--url', url,
+            '--form', 'idList=12345678',
+            '--form', 'pos=top',
+            '--form', 'name=mr_test',
+            '--form', f'fileSource=@{fdata};type=application/pdf',
+        ])
+        assert r.exit_code == 0, f'{r}'
+        r.check_stats(1, 404)
+
+    # issue #11157, send upload that is slowly read in
+    def test_07_33_issue_11157b(self, env: Env, httpd, nghttpx, repeat):
+        proto = 'h2'
+        fdata = os.path.join(env.gen_dir, 'data-10m')
+        # tell our test PUT handler to read the upload more slowly, so
+        # that the send buffering and transfer loop needs to wait
+        url = f'https://{env.authority_for(env.domain1, proto)}/curltest/put?chunk_delay=2ms'
+        curl = CurlClient(env=env)
+        r = curl.run_direct(with_stats=True, args=[
+            '--resolve', f'{env.authority_for(env.domain1, proto)}:127.0.0.1',
+            '--cacert', env.ca.cert_file,
+            '--request', 'PUT',
+            '--max-time', '5', '-v',
+            '--url', url,
+            '--form', 'idList=12345678',
+            '--form', 'pos=top',
+            '--form', 'name=mr_test',
+            '--form', f'fileSource=@{fdata};type=application/pdf',
+        ])
+        assert r.exit_code == 0, f'{r}'
+        r.check_stats(1, 200)
 
     def check_download(self, count, srcfile, curl):
         for i in range(count):