cassandra: Simplify SELECT statement formatting
Test Plan
Failures of release_add_arbitrary will be solved by swh-model!265 (closed); failures of directory_add_arbitrary are unrelated
Migrated from D8182 (view on Phabricator)
Failures of release_add_arbitrary will be solved by swh-model!265 (closed); failures of directory_add_arbitrary are unrelated
Migrated from D8182 (view on Phabricator)