tests/cli/TestBadname: make sure case 5 is never decodable
Sometimes, by chance, case 5 resulted in valid decrypted data:
--- FAIL: TestBadname (0.08s)
cli_test.go:885: Case 5 failed: "J7Rbo1BvfXojpBEr0Qrt_invalid_file GOCRYPTFS_BAD_NAME" in ["file GOCRYPTFS_BAD_NAME,\x9e$O\xc3j\x8c\xd0\x06\x01#\f%k\x02\xcanvalid_file GOCRYPTFS_BAD_NAME,mzaZRF9_0IU-_5vv2wPC_invalid_file GOCRYPTFS_BAD_NAME,file,file_invalid_file GOCRYPTFS_BAD_NAME,mzaZRF9_0IU-_5vv2wP_invalid_file GOCRYPTFS_BAD_NAME"]
Add percent signs so base64 decoding always fails.
Fixes https://github.com/rfjakob/gocryptfs/runs/3347883728
b8ddc49ede