tests: Update encrypted sample files.

* tests/gpg/cipher-1.asc: Update file.
* tests/gpg/cipher-2.asc: Likewise.

Convert the plaintext to UTF-8 and re-create the encrypted file.

• Fixes-commit: a11450eb048df79a3f2b00ebef6d7cab07ad5054
• Signed-off-by: Justus Winter <justus@g10code.com>