chore(relay): pin staging c4 to image G for E-pre (#28854)

G is main 2de73812 (relay sha256:07b5bf67…), which adds the cell's t_preauth latency metric.

Claude-Session: f2fe8cb5-4467-4a25-8aab-98598b70791f

cloud/dev/scripts/relay-staging-c4-refresh-workflow.test.mjs

@@ -42,9 +42,9 @@ const asiaCells = ['production-gce-c27', 'production-gce-c28', 'production-gce-c
 const c30Digest = '4158d8a2e18e9caec439d257f0c1e45d92ffea8c0262f057b2f08c76a134bcf0'
 // C31 launches on the digest the director served when it was declared.
 const c31Digest = 'f30b5cb1ec52b6b6145efecfa1b8be9e3d309403beffd8abcc64197a2087e269'
-// Staging C4 is declared on image F (main 3c1141f2, the six-cell dead-cell rerun); the staging
+// Staging C4 is declared on image G (main 2de73812, E-pre with the t_preauth metric); the staging
 // director deploy binds its digest to this line.
-const stagingC4Digest = '41cba995b288cab70579882ebef23e74c5ee426b6f8924cea7c986aba23bcbfe'
+const stagingC4Digest = '07b5bf67a7706b2a61ef5e9a6d8ce85ee37c2a08609496a94eb5254881b5b87d'
 
 function cellBlock(tfvars, cellId) {
   const start = tfvars.indexOf(`"${cellId}"`)

cloud/infra/terraform/environments/staging.tfvars

@@ -86,7 +86,7 @@ relay_gce_cells = {
     boot_image                  = "https://www.googleapis.com/compute/v1/projects/cos-cloud/global/images/cos-stable-121-18867-528-21"
     capacity_requests           = 6000
     database_pool_max           = 10
-    image                       = "us-central1-docker.pkg.dev/onorca-cloud-staging/orca-cloud/relay@sha256:41cba995b288cab70579882ebef23e74c5ee426b6f8924cea7c986aba23bcbfe"
+    image                       = "us-central1-docker.pkg.dev/onorca-cloud-staging/orca-cloud/relay@sha256:07b5bf67a7706b2a61ef5e9a6d8ce85ee37c2a08609496a94eb5254881b5b87d"
     initially_enabled           = false
     connection_hard_cap         = 3000
     connection_unobserved_bound = 60