[test] fix server/querier/build_descr1 test. There is no self.transaction of TestCase. I assumed the test writer meant a session. This seems to make the test pass.

[server] make `test_bfss_fs_importing_transparency` less verbose on failure Dumping the whole content of a file on failure is a bit annoying. We only print the bad version here (it's usually the file path).

[entity] drop redundant cache update This ``cw_attr_cache`` update is redundant, ``_cw_update_attr_cache`` already do this step.