testing: fix vault setup test's reliance on specific Raft index (#25806)

The test for `nomad setup vault` command expects a specific `CreateIndex` for the
job it creates. Any Raft write when a server comes up or establishes leadership
can cause this test to break. Interpolate the expected index as we've done for
other indexes on the job to make this test less brittle.

Ref: https://github.com/hashicorp/nomad-enterprise/pull/2673#issuecomment-2847619747

command/setup_vault_test.go

@@ -87,7 +87,7 @@ test  default    batch  pending
 			expectedOut: fmt.Sprintf(`{
     "JobsWithoutVaultIdentity": [
         {
-            "CreateIndex": 10,
+            "CreateIndex": %d,
             "Datacenters": [
                 "dc1"
             ],
@@ -111,7 +111,7 @@ test  default    batch  pending
     "OutdatedNodes": [],
     "VaultTokens": null
 }
-`, *job.CreateIndex, *job.ModifyIndex, *job.SubmitTime),
+`, *job.CreateIndex, *job.CreateIndex, *job.ModifyIndex, *job.SubmitTime),
 		},
 		{
 			name: "-check with -t",