test suite: Use 'say' to say something instead of 'test_expect_success'

Some tests report that some tests will be skipped.  They used
'test_expect_success' with a trivially successful test.  Nowadays we have
the helper function 'say' for this purpose.

In on case, 'say_color skip' is replaced by 'say' because the former is
not intended as a public API.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>

t/t9700-perl-git.sh

@@ -7,7 +7,7 @@ test_description='perl interface (Git.pm)'
 . ./test-lib.sh
 
 perl -MTest::More -e 0 2>/dev/null || {
-	say_color skip "Perl Test::More unavailable, skipping test"
+	say "Perl Test::More unavailable, skipping test"
 	test_done
 }