Use apache2 reverse proxy instead of mirror

This MR replaces our mirror address used in the CI with a new apache2 caching reverse proxy setup that is more flexible than the mirroring setup.

@bob: please report weird issues related to conda lookups.

changed title from [bootstrap] Use apache2 reverse proxy instead of mirror to Use apache2 reverse proxy instead of mirror

changed the description

enabled an automatic merge when the pipeline for b4e8b8ad succeeds

merged

mentioned in commit 48bb36ef

mentioned in issue bob#269 (closed)