ruff: enable TC — flake8-type-checking (#11368)

## Problem

`TYPE_CHECKING` is used inconsistently across Python tests.

## Summary of changes
- Update `ruff`: 0.7.0 -> 0.11.2
- Enable TC (flake8-type-checking):
https://docs.astral.sh/ruff/rules/#flake8-type-checking-tc
- (auto)fix all new issues

test_runner/fixtures/workload.py

@@ -3,7 +3,6 @@ from __future__ import annotations
 import threading
 from typing import TYPE_CHECKING
 
-from fixtures.common_types import TenantId, TimelineId
 from fixtures.log_helper import log
 from fixtures.neon_fixtures import (
     Endpoint,
@@ -17,6 +16,8 @@ from fixtures.pageserver.utils import wait_for_last_record_lsn
 if TYPE_CHECKING:
     from typing import Any
 
+    from fixtures.common_types import TenantId, TimelineId
+
 # neon_local doesn't handle creating/modifying endpoints concurrently, so we use a mutex
 # to ensure we don't do that: this enables running lots of Workloads in parallel safely.
 ENDPOINT_LOCK = threading.Lock()