Allow creation of new projects

This change [1] introduced a regression when creating a new project.

Project creation is skipped since the Source#shouldReplicate
check for projects existance in the cache [2], hence the method
should NOT be invoked for new projects.

Check the source configuration, but skipping the cache.
As part of the source configuration check, the
`remote.NAME.createMissingRepositories` flag is checked as well.

Note that the logic is not taking into consideration if a project
is  hidden.
A project could potentially be created on the remote and be
visible until the correct 'refs/meta/config' isn't replicated
from the source.

The same is currently happening for push-replication, hence there
is no regression between the two solutions.

[1]: https://gerrit-review.googlesource.com/c/plugins/pull-replication/+/363004
[2]: https://gerrit.googlesource.com/plugins/pull-replication/+/refs/heads/stable-3.4/src/main/java/com/googlesource/gerrit/plugins/replication/pull/Source.java#376

Bug: Issue 16790
Change-Id: Idd1bd88b8c46d31993896640fd9f9ae071ee034d