Remove serve.ConfigBuilder's ws_doc_root property (#29010)

The ConfigBuilder.ws_doc_root setter is apparently unused, and the
_ws_doc_root property that it sets is never read.

Update the tests to make it clearer how this data ends up in the
config.paths dict, which is what is used in start_http2_server,
start_ws_server, and start_wss_server.
diff --git a/tools/serve/serve.py b/tools/serve/serve.py
index fa3d743..1d70952 100644
--- a/tools/serve/serve.py
+++ b/tools/serve/serve.py
@@ -987,11 +987,6 @@
         else:
             return os.path.join(data["doc_root"], "websockets", "handlers")
 
-    def ws_doc_root(self, v):
-        self._ws_doc_root = v
-
-    ws_doc_root = property(None, ws_doc_root)
-
     def _get_paths(self, data):
         rv = super(ConfigBuilder, self)._get_paths(data)
         rv["ws_doc_root"] = data["ws_doc_root"]
diff --git a/tools/serve/test_serve.py b/tools/serve/test_serve.py
index 4d7fb0a..0a07db7 100644
--- a/tools/serve/test_serve.py
+++ b/tools/serve/test_serve.py
@@ -54,13 +54,16 @@
 
 def test_ws_doc_root_default():
     with ConfigBuilder() as c:
+        assert c.doc_root == localpaths.repo_root
         assert c.ws_doc_root == os.path.join(localpaths.repo_root, "websockets", "handlers")
+        assert c.paths["ws_doc_root"] == c.ws_doc_root
 
 
 def test_init_ws_doc_root():
     with ConfigBuilder(ws_doc_root="/") as c:
         assert c.doc_root == localpaths.repo_root  # check this hasn't changed
         assert c.ws_doc_root == "/"
+        assert c.paths["ws_doc_root"] == c.ws_doc_root
 
 
 def test_set_ws_doc_root():
@@ -69,6 +72,7 @@
     with cb as c:
         assert c.doc_root == localpaths.repo_root  # check this hasn't changed
         assert c.ws_doc_root == "/"
+        assert c.paths["ws_doc_root"] == c.ws_doc_root
 
 
 def test_pickle():
diff --git a/tools/wptserve/wptserve/config.py b/tools/wptserve/wptserve/config.py
index 4265fcd..50d4f51 100644
--- a/tools/wptserve/wptserve/config.py
+++ b/tools/wptserve/wptserve/config.py
@@ -84,7 +84,7 @@
 
 
 class ConfigBuilder(object):
-    """Builder object for setting the wptsync config.
+    """Builder object for setting the wptserve config.
 
     Configuration can be passed in as a dictionary to the constructor, or
     set via attributes after construction. Configuration options must match