Use apt-archive.postgresql.org and fix dpkg dependency issues

[bergner]

Download deb packages from http://apt-archive.postgresql.org rather than http://atalia.postgresql.org, and escape "+" in such download URLs to %2B to ensure download works ok.

Follow-up problems that appear as a consequence of such a change:

• The barman, pgpool2, and libpgpool0 pgdg90+1 deb files referenced by docker files are not available on apt-archive. There are pgdg80+1 and pgdg100+1 variants, and also some that are just called pgdg+1. After some testing I've ended up referencing the pggd+1 ones.
• dpkg dependency problems for pgpool2, libpgpool, and barman. "docker-compose build" still completes ok though but I'm not trusting those builds.
• pgpool 3.6 and 3.7 requires libmemcached11 but 3.3 requires libmemcached10 and that dependency difference is not dealt with.

Unpacking barman (2.4-1.pgdg+1) ...
dpkg: dependency problems prevent configuration of barman:
 barman depends on python-argcomplete; however:
  Package python-argcomplete is not installed.
 barman depends on python-argh; however:
  Package python-argh is not installed.
 barman depends on python-dateutil; however:
  Package python-dateutil is not installed.
 barman depends on python-psycopg2; however:
  Package python-psycopg2 is not installed.
 barman depends on rsync (>= 3.0.4~); however:
  Package rsync is not installed.
...
Unpacking libpgpool0 (3.7.5-2.pgdg80+1) ...
dpkg: dependency problems prevent configuration of libpgpool0:
 libpgpool0 depends on libmemcached11; however:
  Package libmemcached11 is not installed.
...
dpkg: dependency problems prevent configuration of pgpool2:
 pgpool2 depends on libpgpool0 (= 3.7.5-2.pgdg80+1); however:
  Package libpgpool0 is not configured yet.
 pgpool2 depends on postgresql-common (>= 26); however:
  Package postgresql-common is not installed.

All of the above dependency problems are dealt with in this suggested fix and all "docker-compose build" variants complete successfully, and without any dpkg errors.