fix(account): prevent infinite pagination loop and duplicate results

[AleksandrKls]

Changes being requested

Fix infinite/long pagination loop and duplicate results in cloudflare_accounts datasource.

When using an Account API token, the Cloudflare /accounts API may return the same page repeatedly even when result_info.total_pages = 1.

Example behavior observed:

• Requests to /accounts?page=2+ return the same account as page 1
• Pagination does not terminate
• Provider continues calling GetNextPage() until max_items (default 1000)
• Results contain many duplicates of the same account
• terraform plan may take several minutes

This PR adds safeguards to handle non-progressing pagination:

• Deduplicate results by account.id
• Stop pagination when:
  • page content repeats (same length + same first ID)
  • no new unique accounts are added

This ensures fast execution and prevents duplicate results while preserving normal behavior for valid pagination.

Related to #5298

---

Acceptance test run results

• I have added or updated acceptance tests for my changes
• I have run acceptance tests for my changes and included the results below

Steps to run acceptance tests

N/A – no acceptance tests added (bug is specific to Account API token behavior and requires specific account/token setup to reproduce)

Test output

N/A

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Additional context & links

Direct API reproduction using Account API token. Will be returned 5 duplicates:

for p in 1 2 3 4 5; do
  echo "===== PAGE $p ====="
  curl -sS "https://api.cloudflare.com/client/v4/accounts?page=$p&per_page=1" \
    -H "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
    | jq '{page: .result_info.page, per_page: .result_info.per_page, count: (.result | length), total_count: .result_info.total_count, total_pages: .result_info.total_pages, ids: [.result[]?.id]}'
done

[jhutchings1]

I have pinged our engineering team to look at this PR.

accidental approval before test

[AleksandrKls]

@rotem-cloud Sorry, I haven't created pull requests in Open Source before. Just to clarify, are you expecting me to write tests or will you test them yourself?

[AleksandrKls]

@jhutchings1 Could you please clarify the details regarding my question above?

[rupalims]

Hi @AleksandrKls
Our team has some question/concern regarding the MR.
We are standardising pagination scheme.
We have community triage.
Thursday, April 9⋅8:30 – 9:00am PST.
Weekly on Thursday

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Please join to discuss about this

[AleksandrKls]

I don't want to participate in meetings, but I can answer all your questions in text format.

I'd also like to point out that we have a 10-hour time difference. I live in the UTC +3 time zone

[musa-cf]

Hi @AleksandrKls, I'm looking into this and we suspect the root cause actually lies upstream in our Go SDK, so I'm exploring the option to patch it there instead. I'll circle back with an update this week. Thanks for opening the PR and providing these details! It helps a ton.

[musa-cf]

Could you please clarify the details regarding my question above?

As for testing the PR yourself, you're fine. I'll make sure we get the reproduction and test coverage sorted.

[AleksandrKls]

Could you please clarify the details regarding my question above?

As for testing the PR yourself, you're fine. I'll make sure we get the reproduction and test coverage sorted.

It’s not about your Go SDK. The issue lies in how the API behaves when an account API token is used.

You can take my curl request that I attached, send an HTTP request using an account API token (not to be confused with a user token), and you’ll observe the same behavior as with the data resource

[musa-cf]

I've forwarded that info to the IAM team who owns this API to get it sorted in the API layer. Thanks @AleksandrKls