t0000: keep clean-up tests together

We check that test_when_finished cleans up after a test, and that it
runs even after a failure. Those two were originally adjacent, but got
split apart by the new test added in 477dcaddb6 (tests: do not let lazy
prereqs inside `test_expect_*` turn off tracing, 2020-03-26), and then
further by more lazy-prereq tests. Let's move them back together.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0000-basic.sh

@@ -829,17 +829,6 @@ then
 	exit 1
 fi
 
-clean=no
-test_expect_success 'tests clean up after themselves' '
-	test_when_finished clean=yes
-'
-
-if test -z "$GIT_TEST_FAIL_PREREQS_INTERNAL" -a $clean != yes
-then
-	say "bug in test framework: basic cleanup command does not work reliably"
-	exit 1
-fi
-
 test_lazy_prereq NESTED_INNER '
 	>inner &&
 	rm -f outer
@@ -874,6 +863,17 @@ test_expect_success 'lazy prereqs do not turn off tracing' "
 	grep 'echo trace' lazy-prereq-and-tracing/err
 "
 
+clean=no
+test_expect_success 'tests clean up after themselves' '
+	test_when_finished clean=yes
+'
+
+if test -z "$GIT_TEST_FAIL_PREREQS_INTERNAL" -a $clean != yes
+then
+	say "bug in test framework: basic cleanup command does not work reliably"
+	exit 1
+fi
+
 test_expect_success 'tests clean up even on failures' "
 	run_sub_test_lib_test_err \
 		failing-cleanup 'Failing tests with cleanup commands' <<-\\EOF &&