Use DecryptVerifyJob to decrypt and/or verify inline PGP message blocks
The old code was unnecessarily complicated. And it failed to work with GpgME 1.24 because the verify jobs now explicitly ask gpg to perform a signature verification and that causes a failure if the data isn't signed.
The switch to GpgME 1.24 in the CI image caused core-cryptohelpertest to fail out of the blue. The MR makes the test pass again.
Edited by Ingo Klöcker