Revert "bpo-38811: Check for presence of os.link method in pathlib. (GH-17170)" (#17219)

This reverts commit 111772fc27cfe388bc060f019d68a3e33481ec65.
diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index 5142ff6..d70fde0 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -418,12 +418,7 @@
 
     unlink = os.unlink
 
-    if hasattr(os, "link"):
-        link_to = os.link
-    else:
-        @staticmethod
-        def link_to(self, target):
-            raise NotImplementedError("os.link() not available on this system")
+    link_to = os.link
 
     rmdir = os.rmdir
 
@@ -435,7 +430,6 @@
         if supports_symlinks:
             symlink = os.symlink
         else:
-            @staticmethod
             def symlink(a, b, target_is_directory):
                 raise NotImplementedError("symlink() not available on this system")
     else: