Classmethod properties are erroneously "called" in multiple modules

BPO	44904
Nosy	@tim-one, @rhettinger, @serhiy-storchaka, @miss-islington, @AlexWaygood
PRs	bpo-44904: Fix classmethod property bug in doctest module #28838 [3.10] bpo-44904: Fix classmethod property bug in doctest module (GH-28838) #29261 [3.9] bpo-44904: Fix classmethod property bug in doctest module (GH-28838) #29262
Superseder	bpo-45356: Calling `help` executes @classmethod @Property decorated methods
Files	bug_report.py: Example of the issue classmethod_properties_bug.py: Short script demonstrating how a bug relating to classmethod properties causes doctest.py to crash

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-10-10.22:18:34.456>
created_at = <Date 2021-08-12.21:16:41.103>
labels = ['type-bug', '3.9', '3.10', '3.11']
title = 'Classmethod properties are erroneously "called" in multiple modules'
updated_at = <Date 2021-10-28.08:13:53.897>
user = 'https://bugs.python.org/rzepeckit'

bugs.python.org fields:

activity = <Date 2021-10-28.08:13:53.897>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2021-10-10.22:18:34.456>
closer = 'rhettinger'
components = []
creation = <Date 2021-08-12.21:16:41.103>
creator = 'rzepecki.t'
dependencies = []
files = ['50212', '50218']
hgrepos = []
issue_num = 44904
keywords = ['patch']
message_count = 6.0
messages = ['399482', '399622', '403612', '405154', '405156', '405157']
nosy_count = 6.0
nosy_names = ['tim.peters', 'rhettinger', 'serhiy.storchaka', 'miss-islington', 'AlexWaygood', 'rzepecki.t']
pr_nums = ['28838', '29261', '29262']
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '45356'
type = 'behavior'
url = 'https://bugs.python.org/issue44904'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']