Fix tests for MySQL 8.4: add unique index for complex fks#2007

mringler wants to merge 3 commits intopropelorm:masterpropelorm/Propel2:masterfrom

mringler:fix_tests/add_unique_index_for_complex_fksmringler/perpl:fix_tests/add_unique_index_for_complex_fksCopy head branch name to clipboard