fix(google_fastly_waf): Do not serve GET cached responses on OPTIONS requests

[leplatrem]

Description

Since we migrated to Fastly, we cannot navigate the Remote Settings public data from the Admin UI.
Because OPTIONS requests are served cached GET responses.

This PR sends anything but GET/HEAD/FASTLYPURGE to the origins.

Who it affects in webservices-infra

  │       Service       │            Current snippet             │        Effect of the change        │
  ├─────────────────────┼────────────────────────────────────────┼────────────────────────────────────┤
  │ pontoon             │ already has the exact boilerplate      │ none                               │
  │                     │ check                                  │                                    │
  ├─────────────────────┼────────────────────────────────────────┼────────────────────────────────────┤
  │ balrog, monitor,    │ only set the cache header for GET/HEAD │ none                               │
  │ vpn                 │                                        │                                    │
  ├─────────────────────┼────────────────────────────────────────┼────────────────────────────────────┤
  │ fx-sharing          │ only geo-blocks POST /api/v1/create    │ none                               │
  ├─────────────────────┼────────────────────────────────────────┼────────────────────────────────────┤
  │ treeherder          │ sets the cache header for GET, HEAD    │ preflights go to the origin        │
  │ (/assets/*)         │ and OPTIONS                            │ instead of cache                   │
  ├─────────────────────┼────────────────────────────────────────┼────────────────────────────────────┤
  │ mdn                 │ sets the cache header for GET, HEAD    │ preflights go to the origin        │
  │                     │ and OPTIONS                            │ instead of cache                   │
  └─────────────────────┴────────────────────────────────────────┴────────────────────────────────────┘

Related Tickets & Documents

• https://mozilla-hub.atlassian.net/browse/RMST-377

[github-actions]

Release plan

Directory	Previous version	New version
google_fastly_waf	2.30.0	2.31.0

[bkochendorfer]

Great, thank you!