A `defer d.Close()` runs when the test function returns, before its
t.Cleanup functions. The cleanups that delete the test's rows then ran on
a closed pool, the error was ignored, and the rows stayed in the database
for the next run. PR #220 fixed three files; this applies the same pattern
to every remaining db test that combines `defer d.Close()` with row
cleanups.
- Close the pool with t.Cleanup, registered before the row cleanups so it
runs last (LIFO).
- Report cleanup errors with t.Errorf through small helpers in
db/cleanup_helpers_test.go. A profile the test already deleted is not an
error.
Test files only. No assertion or production change.