ipatests: Raise log level of 389-ds replication
    
    - change log level for replication debugging
      According to the docs:
      ```
      default level of logging(16384) used for critical errors and other
      messages that are always written to the error log. Messages at this
      level are always included in the error log, regardless of the log
      level setting.
      ```
    
    - always flush the access logs to filesystem
      During the testing access logs may be written with delay, this
      results in logs are not collected by this test node, but for example,
      the next one.
    
    - as of now, the changes on `cn=config` are made after the installation
      of server or replica. If an error occurs during these stages, then the
      actual log level will be the default and not as expected.
    
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>