Audit tests are vulnerable to noise from LOGIN queries (because AUTH
audit logs can appear at any time). Most tests already use the
`filter_out_noise` mechanism to remove this noise, but tests
focused on AUTH verification did not, leading to sporadic failures.
This change adds a filter to ignore AUTH logs generated by the default
"cassandra" user, so tests only verify logs from the user created
specifically for each test.
Fixes: scylladb/scylladb#25069
(cherry picked from commit aef6474537)
12866e8f2e