ROCK definitions for v2.6.3 and v2.9.3.

[aznashwan]

This PR notably contains:

• ROCK definitions for older versions for each component (v2.6.3 and v2.9.3)
• parametrized sanity and integration tests for all rocks over all versions/architectures
• fix for harbor-db locale issues

Notes for reviewers:

The vast majority of the older ROCKs have virtually no differences except for the source-tag of the repo being pulled, or the version of go/node snaps installed, with the only notable differences being:

• v2.6.3/harbor-portal/rockcraft.yaml: almost completely different build steps from the later versions so worth reviewing
• v2.6.3/harbor-db/rockcraft.yaml: only installs PostgreSQL 13, while the later versions install both 13 and 14

TODOs:

• fix integration tests on GitHub runners (currently the tests only deploy the upstream Helm chart without actually checking any of the services so the final image manifests can get published)
• translate various HEALTHCHECK definitions as detailed in Define Pebble healthchecks for Harbo component images which feature them. #13

[bschimke95]

LGTM, great work!