This:
- Actually installs the reverse proxy part to serve sentry request
- Update varnish reverse proxy to allow specific icinga checks (to conserve actual sentry checks as is).
- No impact on riverside node regarding sentry (besides its vagrant ip change)
- Installs a rewrite rule on the pergamon reverse proxy to conserve the sentry.s.o resolution as is the time the ttl expiry happens [1]
[1] sentry.s.o will change from targetting pergamon to targetting swh-rproxy3.inria.fr
Related to T3891