gh-103053: Run tools test_freeze on buildbot

No longer skip test_tools.test_freeze on buildbots.

Remove test.support.skip_if_buildbot() function.

The skip was added when freeze tests were added in
commit 13d9205.

Author: vstinner

Lib/test/support/__init__.py

@@ -384,17 +384,6 @@ def wrapper(*args, **kw):
     return decorator
 
 
-def skip_if_buildbot(reason=None):
-    """Decorator raising SkipTest if running on a buildbot."""
-    if not reason:
-        reason = 'not suitable for buildbots'
-    try:
-        isbuildbot = getpass.getuser().lower() == 'buildbot'
-    except (KeyError, EnvironmentError) as err:
-        warnings.warn(f'getpass.getuser() failed {err}.', RuntimeWarning)
-        isbuildbot = False
-    return unittest.skipIf(isbuildbot, reason)
-
 def check_sanitizer(*, address=False, memory=False, ub=False):
     """Returns True if Python is compiled with sanitizer support"""
     if not (address or memory or ub):

Lib/test/test_tools/test_freeze.py

@@ -14,7 +14,6 @@
 
 @support.requires_zlib()
 @unittest.skipIf(sys.platform.startswith('win'), 'not supported on Windows')
-@support.skip_if_buildbot('not all buildbots have enough space')
 # gh-103053: Skip test if Python is built with Profile Guided Optimization
 # (PGO), since the test is just too slow in this case.
 @unittest.skipIf(support.check_cflags_pgo(),