GH-127381: pathlib ABCs: remove case_sensitive argument (#131024)

Remove the *case_sensitive* argument from `_JoinablePath.full_match()` and
`_ReadablePath.glob()`. Using a non-native case sensitivity forces the use
of "case-pedantic" globbing, where we `iterdir()` even for non-wildcard
pattern segments. But it's hard to know when to enable this mode, as
case-sensitivity can vary by directory, so `_PathParser.normcase()` doesn't
always give the full picture. The `Path.glob()` implementation is forced to
make an educated guess, but we can avoid the issue in the ABCs by dropping
the *case_sensitive* argument.

(I probably shouldn't have added these arguments in `PurePath` and `Path`
in the first place!)

Also drop support for `_ReadablePath.glob(recurse_symlinks=False)`, which
makes recursive globbing much slower.

Lib/test/test_pathlib/test_pathlib_abc.py

@@ -709,18 +709,6 @@ class ReadablePathTest(JoinablePathTest):
         p = P(self.base)
         self.assertEqual(list(p.glob("")), [p.joinpath("")])
 
-    def test_glob_case_sensitive(self):
-        P = self.cls
-        def _check(path, pattern, case_sensitive, expected):
-            actual = {str(q) for q in path.glob(pattern, case_sensitive=case_sensitive)}
-            expected = {str(P(self.base, q)) for q in expected}
-            self.assertEqual(actual, expected)
-        path = P(self.base)
-        _check(path, "DIRB/FILE*", True, [])
-        _check(path, "DIRB/FILE*", False, ["dirB/fileB"])
-        _check(path, "dirb/file*", True, [])
-        _check(path, "dirb/file*", False, ["dirB/fileB"])
-
     def test_info_exists(self):
         p = self.cls(self.base)
         self.assertTrue(p.info.exists())