The following is an excerption from the WL.
1. Change so that MIXED is default format
1.1 to change the default for command line --binlog-format
1.2 to alter global_system_variables.binlog_format calculation
basing on command line --binlog-format parameter and
its default.
2. Change test suite so that more testing is done by MIXED format.
2.1 to check if there are test cases requiring --binlog-foramt=statement via
`source include/have_binlog_format_statement.inc' and affected by
altering the latter to be "mixed".
2.2 to check the content of such vulnerable cases to find if
extending to the mixed does not modify results. In that case simply
substitute source arguments as explained.
2.3 if a test in mixed mode deals with features triggering
row-binlogging then if necessary we can switch explicitly
to statement mode or create another test to run with
non-recommended STATEMENT mode
Particullarily, extracting INSERT DELAYED
binlogging subtest for statement mode is performed, and
the snippet is moved into a separate test file.
Note that since now all three modes verify this use case
through 3 different tests.
No changes in item 3 of HLD appeared to be needed.
