Clean up output from pending migrations middleware. #813

Job	Run time
Windows - PHP 8.1 & SQL Server	2m 47s
testsuite-linux (8.1, mariadb)	1m 33s
testsuite-linux (8.1, mysql)	1m 12s
testsuite-linux (8.1, pgsql)	54s
testsuite-linux (8.1, sqlite)	47s
testsuite-linux (8.2, mariadb)	1m 36s
testsuite-linux (8.2, mysql)	59s
testsuite-linux (8.2, pgsql)	52s
cs-stan / Coding Standard & Static Analysis	53s
testsuite-linux (8.2, sqlite)	1m 8s
testsuite-linux (8.3, mariadb)	1m 33s
testsuite-linux (8.3, mysql)	1m 9s
testsuite-linux (8.3, pgsql)	1m 11s
testsuite-linux (8.3, sqlite)	43s
testsuite-linux (8.4, mariadb)	1m 44s
testsuite-linux (8.4, mysql)	1m 4s
testsuite-linux (8.4, pgsql)	1m 2s
testsuite-linux (8.4, sqlite)	44s
testsuite-linux (8.1, sqlite, prefer-lowest)	55s
testsuite-linux (8.1, sqlite, dev-5.next as 5.1.0)	46s
	23m 32s

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