t: change which user is deleted from table

Problem: There is a test in t1023-flux-account-banks.t that makes sure
the default bank of a user is updated when one of their user/bank rows
is deleted from the database by removing it in the test prior, but the
wrong user is deleted.

Change which user is deleted in t1023-flux-account-banks.t.

t/t1023-flux-account-banks.t

@@ -110,7 +110,7 @@ test_expect_success 'add a user to two different banks' '
 '
 
 test_expect_success 'delete user default bank row' '
-	flux account delete-user user5013 E
+	flux account delete-user user5015 E
 '
 
 test_expect_success 'check that user default bank gets updated to other bank' '