Fix for flakiness in socket tests. NFC (emscripten-core#23103)

In emscripten-core#22987 I added a new veriant of the test_nodejs_sockets_echo test and
chose the next consecutive port number, but it seems that each test ends
up using two ports numbers so this could conflicted with the tests that
were using both the previous and next number in the sequence (59164 and
59166).

test/test_sockets.py

@@ -285,7 +285,7 @@ def test_enet(self):
     'native': [WebsockifyServerHarness, 59160, ['-DTEST_DGRAM=0']],
     'tcp': [CompiledServerHarness, 59162, ['-DTEST_DGRAM=0']],
     'udp': [CompiledServerHarness, 59164, ['-DTEST_DGRAM=1']],
-    'pthread': [CompiledServerHarness, 59165, ['-pthread', '-sPROXY_TO_PTHREAD']],
+    'pthread': [CompiledServerHarness, 59166, ['-pthread', '-sPROXY_TO_PTHREAD']],
   })
   def test_nodejs_sockets_echo(self, harness_class, port, args):
     if harness_class == WebsockifyServerHarness and common.EMTEST_LACKS_NATIVE_CLANG:
@@ -304,12 +304,12 @@ def test_nodejs_sockets_echo_subprotocol(self):
     # Test against a Websockified server with compile time configured WebSocket subprotocol. We use a Websockified
     # server because as long as the subprotocol list contains binary it will configure itself to accept binary
     # This test also checks that the connect url contains the correct subprotocols.
-    with WebsockifyServerHarness(test_file('sockets/test_sockets_echo_server.c'), [], 59166):
-      self.run_process([EMCC, '-Werror', test_file('sockets/test_sockets_echo_client.c'), '-o', 'client.js', '-sSOCKET_DEBUG', '-sWEBSOCKET_SUBPROTOCOL="base64, binary"', '-DSOCKK=59166'])
+    with WebsockifyServerHarness(test_file('sockets/test_sockets_echo_server.c'), [], 59168):
+      self.run_process([EMCC, '-Werror', test_file('sockets/test_sockets_echo_client.c'), '-o', 'client.js', '-sSOCKET_DEBUG', '-sWEBSOCKET_SUBPROTOCOL="base64, binary"', '-DSOCKK=59168'])
 
       out = self.run_js('client.js')
       self.assertContained('do_msg_read: read 14 bytes', out)
-      self.assertContained(['connect: ws://127.0.0.1:59166, base64,binary', 'connect: ws://127.0.0.1:59166/, base64,binary'], out)
+      self.assertContained(['connect: ws://127.0.0.1:59168, base64,binary', 'connect: ws://127.0.0.1:59168/, base64,binary'], out)
 
   @requires_native_clang
   def test_nodejs_sockets_echo_subprotocol_runtime(self):