test(conformance): GRAPH_BACKEND=true|false (#190)

Tests  conformance with block and CAR backends separately.

.github/workflows/gateway-conformance.yml

@@ -75,6 +75,10 @@ jobs:
           specs: +trustless-gateway,+path-gateway,+subdomain-gateway,+dnslink-gateway,+redirects-file
           # use below to skip specific test if needed
           # args: -skip 'TestFooBr/GET_response_for_something'
+          #
+          # only-if-cached: bifrost-gateway does not guarantee local cache, we will adjust upstream test (which was Kubo-specific)
+          # for now disabling these test cases
+          args: -skip 'TestGatewayCache/.*_for_/ipfs/_with_only-if-cached_succeeds_when_in_local_datastore'
 
       # 7. Upload the results
       - name: Upload MD summary