mysqlbinlog_have_debug.inc

There's mysqlbinlog_have_debug.inc in mysql-test/include/, unused until surfaced by this (hallucinated?) open PR.
It originates from ancient times for a technically true but practically strange reason: It's possible to build mariadbd in Release mode but mariadb-binlog in Debug (or vice versa).

To decide:

• Don't support this type of setup → delete this dead code file.
• Do support this type of setup → fix numerous mariadb-binlog tests (MDEV-40544, MDEV-40674, likely more) to check the build type on the correct site(s).
  • Ideally: Rather than scanning the entire mariadb-binlog --help, implement an alternative, more efficient solution.
    (have_debug.inc uses suite.pm results, which scans the entire mariadbd --help for other feature detection reasons.)