[BUG] cnf testsuite doesn't work behind proxy

[collivier]

Describe the bug

HTTP::Client doesn't support proxy which forbids defacto using cnf-testsuite behind corporate proxies.
Here are some calls to HTTP:Client https://github.com/search?q=repo%3Acnti-testcatalog%2Ftestsuite%20http%2Fclient&type=code

Please see

• the upstream issues in HTTP::Client proxy support crystal-lang/crystal#2963
• the related patchset which has not been merged yet (and not updated for more than a year) https://github.com/crystal-lang/crystal/pull/13063/files

A workaround could be to patch crystal via the last patchset still in draft or to rather call external binaries

Please note that Sylva (at least the Orange platforms) are behind corporate proxies.

[collivier]

By applying the patch, and testing via coredns all pass except

• non_root_containers
• specialized_init_system
• zombie_handled
• sig_term_handled