Add new signer in 'testing-preview'

This requires to update the host machine with more memory.

Author: jpraynaud

.github/workflows/ci.yml

@@ -439,6 +439,10 @@ jobs:
             }
           mithril_signers: |
             {
+              "1" = {
+                type    = "verified",
+                pool_id = "",
+              },
               "2" = {
                 type    = "verified",
                 pool_id = "",
@@ -451,7 +455,7 @@ jobs:
           terraform_backend_bucket: hydra-terraform-admin
           google_region: europe-west1
           google_zone: europe-west1-b
-          google_machine_type: e2-standard-2
+          google_machine_type: e2-highmem-2
 
     runs-on: ubuntu-22.04