Textract polling exec should assembly block array

[DenovVasil]

Now polling exec return last GetDocumentAnalysisResult.
this bug relate to #2923

Steps to Reproduce

1. run textract connector with polling exec.

Expected Behavior

So basically if a response has a nextToken set, query again with the nextToken passed. Keep doing it until you get a response without nextToken.
What you should see (from my tests, but do double check) is that each response has the same metadata plus an array of blocks - the blocks differ and are what needs assembly.
So collect all responses with nextToken, then merge the responses into a single response for the process. Which should result in all blocks for the document being return, ie more than 1k if a long document.

requirements discussions https://camunda.slack.com/archives/D07K9UZRU57/p1724923821671829

Environment

• OS: [e.g. Windows 7]
• Library version: [e.g. 2.0.0]
• Camunda version: [e.g. 8.0.4 (self-managed)]