Merge pull request #14113 from vbotbuildovich/backport-pr-14032-v23.2…

….x-106

[v23.2.x] cloud_storage/ducktape: Wait for chunk observer to stop

tests/rptest/tests/cloud_storage_chunk_read_path_test.py

@@ -346,6 +346,9 @@ def test_read_when_cache_smaller_than_segment_size(self):
 
         self._consume_baseline(timeout=180, max_msgs=read_count)
         observe_cache_dir.stop()
+        observe_cache_dir.join(timeout=10)
+        assert not observe_cache_dir.is_alive(
+        ), 'cache observer is unexpectedly alive'
 
         self._assert_not_in_cache(fr'.*kafka/{self.topic}/.*\.log\.[0-9]+$')
         self._assert_in_cache(f'.*kafka/{self.topic}/.*_chunks/[0-9]+')