qa/tasks/ceph_manager: population must be a sequence

This patch addresses TypeError message for rados_bench if there is
python3.11 for example.

    2025-04-17T17:05:45.719 INFO:tasks.thrashosds.thrasher:Traceback (most recent call last):
      File "/home/debian/src/github.com_kshtsk_ceph_b8b19a59890781db2f405500155c975cbdeb38a1/qa/tasks/ceph_manager.py", line 192, in wrapper
        return func(self)
               ^^^^^^^^^^
      File "/home/debian/src/github.com_kshtsk_ceph_b8b19a59890781db2f405500155c975cbdeb38a1/qa/tasks/ceph_manager.py", line 1439, in _do_thrash
        self.choose_action()()
      File "/home/debian/src/github.com_kshtsk_ceph_b8b19a59890781db2f405500155c975cbdeb38a1/qa/tasks/ceph_manager.py", line 855, in grow_pool
        pool = self.ceph_manager.get_pool()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/home/debian/src/github.com_kshtsk_ceph_b8b19a59890781db2f405500155c975cbdeb38a1/qa/tasks/ceph_manager.py", line 2221, in get_pool
        return random.sample(self.pools.keys(), 1)[0]
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.11/random.py", line 439, in sample
        raise TypeError("Population must be a sequence.  "
    TypeError: Population must be a sequence.  For dicts or sets, use sorted(d).

This happens because dict.keys() returns dict_keys() instead of list,
however the random.sample() accepts a list only as first argument
because sampling from a set deprecated since Python 3.9 and eventually
removed since 3.11 version.

Signed-off-by: Kyr Shatskyy <[email protected]>

Author: Kyr Shatskyy

qa/tasks/ceph_manager.py

@@ -2298,7 +2298,7 @@ def get_pool(self):
         """
         with self.lock:
             if self.pools:
-                return random.sample(self.pools.keys(), 1)[0]
+                return random.sample(list(self.pools.keys()), 1)[0]
 
     def get_pool_pg_num(self, pool_name):
         """