test: set AuthToken in tests to match Client code

[schmichael]

tl;dr - runtime code is fine but tests should match reality

The Nomad Client Agent is the only consumer of the Node.Derive{SI,Vault}Token RPCs, therefore tests of the RPCs should match Nomad Client behavior.

• DeriveVaultToken code:

  nomad/client/client.go

  Lines 2904 to 2917 in a9ee66a

  	// DeriveVaultToken of nomad server can take in a set of tasks and
  	// creates tokens for all the tasks.
  	req := &structs.DeriveVaultTokenRequest{
  	NodeID: c.NodeID(),
  	SecretID: c.secretNodeID(),
  	AllocID: alloc.ID,
  	Tasks: verifiedTasks,
  	QueryOptions: structs.QueryOptions{
  	Region: c.Region(),
  	AllowStale: false,
  	MinQueryIndex: alloc.CreateIndex,
  	AuthToken: c.secretNodeID(),
  	},
  	}

• DeriveSIToken code:

  nomad/client/client.go

  Lines 2988 to 2997 in a9ee66a

  	req := &structs.DeriveSITokenRequest{
  	NodeID: c.NodeID(),
  	SecretID: c.secretNodeID(),
  	AllocID: alloc.ID,
  	Tasks: tasks,
  	QueryOptions: structs.QueryOptions{
  	Region: c.Region(),
  	AuthToken: c.secretNodeID(),
  	},
  	}

Both of those client code paths include the Node SecretID in both the request's SecretID field as well as the embedded
QueryOptions.AuthToken field.

This patch updates server tests to match that behavior. The tests pass either way.

Description

Testing & Reproduction steps

Links

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[jrasell]

LGTM!