btrfs: tests: drop messages when some tests finish

The messages like 'extent I/O tests finished' are redundant, if the test
fails it's quite obvious in the log and hang is also noticeable. No
other then extent_io and free space tree tests print that so make it
consistent.

Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tests/free-space-tests.c

@@ -876,6 +876,5 @@ out:
 	btrfs_free_dummy_block_group(cache);
 	btrfs_free_dummy_root(root);
 	btrfs_free_dummy_fs_info(fs_info);
-	test_msg("free space cache tests finished");
 	return ret;
 }