Fix: Sitemap Document Loader Tests and Documentation (#11866)

**Description:**
While working on the Docusaurus site loader #9138, I noticed some
outdated docs and tests for the Sitemap Loader.

**Issue:** 
This is tangentially related to #6691 in reference to doc links. I plan
on digging in to a few of these issue when I find time next.

libs/langchain/tests/integration_tests/document_loaders/test_sitemap.py

@@ -11,7 +11,7 @@ def test_sitemap() -> None:
     loader = SitemapLoader("https://langchain.readthedocs.io/sitemap.xml")
     documents = loader.load()
     assert len(documents) > 1
-    assert "🦜🔗" in documents[0].page_content
+    assert "LangChain Python API" in documents[0].page_content
 
 
 def test_sitemap_block() -> None:
@@ -21,7 +21,7 @@ def test_sitemap_block() -> None:
     )
     documents = loader.load()
     assert len(documents) == 1
-    assert "🦜🔗" in documents[0].page_content
+    assert "LangChain Python API" in documents[0].page_content
 
 
 def test_sitemap_block_only_one() -> None:
@@ -31,7 +31,7 @@ def test_sitemap_block_only_one() -> None:
     )
     documents = loader.load()
     assert len(documents) > 1
-    assert "🦜🔗" in documents[0].page_content
+    assert "LangChain Python API" in documents[0].page_content
 
 
 def test_sitemap_block_blocknum_default() -> None:
@@ -41,7 +41,7 @@ def test_sitemap_block_blocknum_default() -> None:
     )
     documents = loader.load()
     assert len(documents) > 1
-    assert "🦜🔗" in documents[0].page_content
+    assert "LangChain Python API" in documents[0].page_content
 
 
 def test_sitemap_block_size_to_small() -> None:
@@ -76,11 +76,11 @@ def test_filter_sitemap() -> None:
     """Test sitemap loader."""
     loader = SitemapLoader(
         "https://langchain.readthedocs.io/sitemap.xml",
-        filter_urls=["https://python.langchain.com/en/stable/"],
+        filter_urls=["https://api.python.langchain.com/en/stable/"],
     )
     documents = loader.load()
     assert len(documents) == 1
-    assert "🦜🔗" in documents[0].page_content
+    assert "LangChain Python API" in documents[0].page_content
 
 
 def test_sitemap_metadata() -> None:
@@ -128,7 +128,7 @@ def test_sitemap_metadata_default() -> None:
 def test_local_sitemap() -> None:
     """Test sitemap loader."""
     file_path = Path(__file__).parent.parent / "examples/sitemap.xml"
-    loader = SitemapLoader(str(file_path))
+    loader = SitemapLoader(str(file_path), is_local=True)
     documents = loader.load()
     assert len(documents) > 1
-    assert "🦜🔗" in documents[0].page_content
+    assert "🦜️🔗" in documents[0].page_content

libs/langchain/tests/integration_tests/examples/sitemap.xml

@@ -1,35 +1,35 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
-        xmlns:xhtml="http://www.w3.org/1999/xhtml">
-  
+  xmlns:xhtml="http://www.w3.org/1999/xhtml">
+
   <url>
     <loc>https://python.langchain.com/en/stable/</loc>
-    
-    
+
+
     <lastmod>2023-05-04T16:15:31.377584+00:00</lastmod>
-    
+
     <changefreq>weekly</changefreq>
     <priority>1</priority>
   </url>
-  
+
   <url>
     <loc>https://python.langchain.com/en/latest/</loc>
-    
-    
+
+
     <lastmod>2023-05-05T07:52:19.633878+00:00</lastmod>
-    
+
     <changefreq>daily</changefreq>
     <priority>0.9</priority>
   </url>
-  
+
   <url>
     <loc>https://python.langchain.com/en/harrison-docs-refactor-3-24/</loc>
-    
-    
+
+
     <lastmod>2023-03-27T02:32:55.132916+00:00</lastmod>
-    
+
     <changefreq>monthly</changefreq>
     <priority>0.8</priority>
   </url>
-  
-</urlset>
+
+</urlset>