Revert "Bug 575541 - [pgp] P2 should not fail completely if a public key is not"

Later steps of verification assume all signatures got verified, so chaning this
invariant can invalidate the whole process.
Instead, work must be placed on providers of signatures to ensure they also provide
the pgp.publicKeys to verify the signatures.

This reverts commit c193e5197535846f3f546f0e9ce210660c190484.

Change-Id: I1dc2cacd044f1ab878001ffef29167867d63c0fe
Reviewed-on: https://git.eclipse.org/r/c/equinox/rt.equinox.p2/+/189738
Tested-by: Equinox Bot <equinox-bot@eclipse.org>
Reviewed-by: Mickael Istria <mistria@redhat.com>
4 files changed