Stabilize RUF060

[ntBre]

Tests look good, just two very small comma changes to the docs

I cherry-picked the docs changes from last time (#20231)

https://docs.astral.sh/ruff/rules/in-empty-collection/

[astral-sh-bot]

ruff-ecosystem results

Linter (stable)

ℹ️ ecosystem check detected linter changes. (+4 -0 violations, +0 -0 fixes in 2 projects; 53 projects unchanged)

zulip/zulip (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --no-fix --output-format concise --no-preview --select ALL

+ tools/lib/provision.py:155:77: RUF060 Unnecessary membership test on empty collection

pytest-dev/pytest (+3 -0 violations, +0 -0 fixes)

+ testing/test_assertrewrite.py:630:20: RUF060 Unnecessary membership test on empty collection
+ testing/test_assertrewrite.py:630:32: RUF060 Unnecessary membership test on empty collection
+ testing/test_assertrewrite.py:637:39: RUF060 Unnecessary membership test on empty collection

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
RUF060	4	4	0	0	0

Linter (preview)

✅ ecosystem check detected no linter changes.