fix(pipelineStage): Rendering with a warning with the pipelineParameters are defined as a SpeL expression

[christosarvanitis]

Although not used by many a user can define the pipelineParameters in the pipeline json as a single SpeL expression and this will be evaluated by Orca during the execution.
Deck however doesnt render this correctly.

Stage json:

{
  "application": "testpipline",
  "failPipeline": true,
  "name": "Pipeline",
  "pipeline": "497ba489-beef-4e60-badb-32f2798c8fac",
  "pipelineParameters": "${{parameters.p1: parameters.p2}}",
  "type": "pipeline",
  "waitForCompletion": true
}

Before the fix:

After the fix: