Fix 3 ERM regressions introduced by Spend Request / IC inbox changes

[Copilot]

PR #9391 introduced 3 ERM failures in LegacyTestsBucket1: 1 new Spend Request regression and 2 NL intercompany tests that now stop on the Complete IC Inbox Action request page. This change aligns the affected tests with the new Spend Request and IC inbox behavior without weakening coverage.

• Spend Request regression

  • Fix CannotModifyReleasedSpendRequest to assert on an actual guarded mutation instead of a no-op Modify(true).
  • The test now validates a field (Purpose) so it exercises TestStatusOpen() on released requests.

• NL intercompany request-page handling

  • Add the existing RequestPageHandler to:
    • AutoAcceptICGenJnlTransactionUT
    • OpenICPurchaseInvoiceWithVendorOrderNoExceeding20Chars
  • This lets both flows continue through Complete IC Inbox Action after the PR introduced request-page-driven behavior on those paths.

• Why this is the minimal fix

  • No product behavior changed.
  • Coverage remains the same: the Spend Request test still verifies the released-state guard, and the intercompany tests still validate journal/document creation outcomes.

// Before: no-op, did not hit the released-state guard
asserterror SpendRequest.Modify(true);

// After: real field validation, exercises TestStatusOpen()
asserterror SpendRequest.Validate(Purpose, LibraryUtility.GenerateGUID());