gh-119452: Remove select, skip 'truncated' test

This removes the select added in commit 29c657a.

As Greg put it in https://github.com/python/cpython/pull/119455/files#r2580052775:
> why select at all here given we just want to block on reading another chunk?
> if the socket closes or errors, that'd return anyways.

This makes the function wait forever for the query body.
Thus, the new test 'test_large_content_length_truncated' times out.
This was the case before the fix, too.

Author: encukou

Lib/http/server.py

@@ -1290,8 +1290,7 @@ def run_cgi(self):
             if self.command.lower() == "post" and nbytes > 0:
                 cursize = 0
                 data = self.rfile.read(min(nbytes, _MIN_READ_BUF_SIZE))
-                while (len(data) < nbytes and len(data) != cursize and
-                       select.select([self.rfile._sock], [], [], 0)[0]):
+                while len(data) < nbytes and len(data) != cursize:
                     cursize = len(data)
                     # This is a geometric increase in read size (never more
                     # than doubling our the current length of data per loop

Lib/test/test_httpservers.py

@@ -1131,6 +1131,7 @@ def test_large_content_length(self):
             res = self.request('/cgi-bin/file7.py', 'POST', body, headers)
             self.assertEqual(res.read(), b'%d %d' % (size, size) + self.linesep)
 
+    @unittest.skipIf(True, "Waits forever for input")
     def test_large_content_length_truncated(self):
         for w in range(18, 65):
             size = 1 << w