Post-push fix for BUG#39934

Moved decide_logging_format to sql_class.cc

sql/sql_base.cc:
  Moved decide_logging_format to sql_class.cc
  The auxiliary macro FLAGSTR is not needed here any more.
sql/sql_class.cc:
  - Moved decide_logging_format from sql_base.cc to here.
  - To avoid copying the FLAGSTR macro, I changed some
    DBUG_PRINT to just print flags in hex. No need to
    pretty-print debug traces.
  - Changed the type of 'flags' to handler::Table_flags
    because that's the return type of handler::ha_table_flags.