fix: Make AWS credential work with global AWS services

[elsmr]

Summary

AWS credential was incorrectly setting region to amazonaws when there is no region in the URL.
For global AWS services this is the case, for example: iam.amazonaws.com.

Workflow to reproduce the issue can be found in Linear.

Related tickets and issues

https://linear.app/n8n/issue/NODE-1335/aws-credential-iam-region-issues

Review / Merge checklist

• PR title and summary are descriptive. Remember, the title automatically goes into the changelog. Use (no-changelog) otherwise. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.

  A bug is not considered fixed, unless a test is added to prevent it from happening again.
  A feature is not complete without tests.

[netroy]

With the amount of checks this credential file has, I think we should start adding unit tests for it.

[cypress]

2 flaky tests on run #5326 ↗︎

0

356

0

0

2

Details:

🌳 🖥️ browsers:node18.12.0-chrome107 🤖 elsmr 🗃️ e2e/*
Project: n8n	Commit: f56d2b0d8b
Status: Passed	Duration: 05:04 💡
Started: Jun 5, 2024 2:31 PM	Ended: Jun 5, 2024 2:37 PM

  cypress/e2e/5-ndv.cy.ts • 2 flaky tests

View Output Video

Test		Artifacts
NDV > should not retrieve remote options when required params throw errors		Screenshots Video
NDV > Stop listening for trigger event from NDV		Screenshots Video

Review all test suite changes for PR #9631 ↗︎

[github-actions]

✅ All Cypress E2E specs passed

[janober]

Got released with n8n@1.45.0