[API tests] Assign a number series to API vendor payment journals

[Prangshuman Das (t-prda)]

Review focus: the number series in LibraryGraphJournalLines.

Area fix (previously #11228): ensures a vendor-payment journal number series, then re-enables the affected tests.

Related: AB#646383, AB#653393

Stack (each PR shows only its own layer; merge bottom first)

1. [API tests] Default to web service key authentication #12674 A: web service key auth (base: main)
2. [Expense tests] Re-enable Expense Agent API tests #12675 B: Expense API tests + clean test codeunit execution
3. [API tests] Re-enable APIV1 and APIV2 API tests #12676 C: re-enable APIV1/APIV2 API tests
4. Area fixes: [API tests] Ensure VAT posting setup in API document fixtures #12677 D1 VAT fixtures → [API tests] Ensure cancellation reason codes in API sales document tests #12678 D2 cancellation reasons → [API tests] Handle localized purchase invoice payment discounts in APIV1 tests #12679 D3 localized discounts → [API tests] Set sales quote document and posting dates in API tests #12680 D4 quote dates → [API tests] Assign a number series to API vendor payment journals #12681 D5 journal numbering → [API tests] Ignore localized fields in API document comparisons #12682 D6 field comparison → [API tests] Return shipment PDF selection and pdfDocument test isolation #12683 D7 PDF documents → [API tests] Improve APIV1 fixture and verification reliability #12684 D8 APIV1 reliability

Experiments (on D8, do not merge): #12685 E single tenant, #12686 F no clean execution. Combined validation (do not merge): #12687, same tree as D8.

Platform: main already pins BCPlatform 30.0.56112.0, which includes the SQL connection-pool fix (AB#653457).

Note for CI: AL-Go's new-warning check needs a CI/CD baseline from the base branch, and features/* bases have none, so a PR build there fails with a 404. The current CI runs were triggered while these PRs targeted main, so their results are valid for the cumulative change.