tests: Don't try to corrupt sqlite database during test.

tests: Don't try to corrupt sqlite database during test.

In run-debuginfod-federation-sqlite.sh we used to try to corrupt
the sqlite database while the debuginfod server was running and
check it detected errors, but that was unreliably and slightly
dangerous since part of the database was already mapped into memory.
Instead trigger some some random activity, then trigger a shutdown.

Signed-off-by: Mark Wielaard <mark@klomp.org>