bugfix: azapi_data_plane_resource doesn't support 204 status code

[dinigo]

fix #1048

Fix the issue when UPSERTING a dataplane resource when the resource already exists. In this case the API answers with a 204 instead of a 200/201.

╷
│ Error: Failed to create/update resource
│ 
│   with azapi_data_plane_resource.works_council_index,
│   on rag.tf line 20, in resource "azapi_data_plane_resource" "rag_index":
│   20: resource "azapi_data_plane_resource" "rag_index" {
│ 
│ creating/updating "Resource: (ResourceId \"rag-westeurope.search.windows.net/indexes('rag-index')\" / Api Version \"2025-09-01\")": PUT
│ https://rag-westeurope.search.windows.net/indexes('rag-index')
│ --------------------------------------------------------------------------------
│ RESPONSE 204: 204 No Content
│ ERROR CODE UNAVAILABLE
│ --------------------------------------------------------------------------------
│ Response contained no body
│ --------------------------------------------------------------------------------
│

This implements the same bugfix as #441

[dinigo]

@magodo , I've seen you moderate and approve most of the PRs around here. Can you help with this PR? thanks a lot

[ms-henglu]

Hi @dinigo , thank you so much for taking time to open this PR!

The fix looks good, but I think it should be added to the create/update method instead of the action method. Please check.

[dinigo]

I built locally and overriding the registry provider in .terraformrc, seems to be working for all ops:

• creating
• updating
• destrying