`azuredevops_serviceendpoint_generic` -Relax URL restrictions

[xuzhang3]

All Submissions:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] I have updated the documentation accordingly.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.
• [x] My code follows the code style of this project.
• [x] I ran lint checks locally prior to submission.
• [x] Have you checked to ensure there aren't other open PRs for the same update/change?

What about the current behavior has changed?

Fixes: #811

=== RUN   TestAccServiceEndpointGeneric_basic
=== PAUSE TestAccServiceEndpointGeneric_basic
=== RUN   TestAccServiceEndpointGeneric_complete
=== PAUSE TestAccServiceEndpointGeneric_complete
=== RUN   TestAccServiceEndpointGeneric_update
=== PAUSE TestAccServiceEndpointGeneric_update
=== RUN   TestAccServiceEndpointGeneric_requiresImportErrorStep
=== PAUSE TestAccServiceEndpointGeneric_requiresImportErrorStep
=== CONT  TestAccServiceEndpointGeneric_basic
=== CONT  TestAccServiceEndpointGeneric_update
=== CONT  TestAccServiceEndpointGeneric_complete
=== CONT  TestAccServiceEndpointGeneric_requiresImportErrorStep
--- PASS: TestAccServiceEndpointGeneric_basic (83.99s)
--- PASS: TestAccServiceEndpointGeneric_complete (84.45s)
--- PASS: TestAccServiceEndpointGeneric_requiresImportErrorStep (293.81s)
--- PASS: TestAccServiceEndpointGeneric_update (324.95s)
PASS
ok      github.com/microsoft/terraform-provider-azuredevops/azuredevops/internal/acceptancetests        332.706s

Does this introduce a change to go.mod, go.sum or vendor/?

• [ ] Yes
• [x] No

Does this introduce a breaking change?

• [ ] Yes
• [x] No

Any relevant logs, error output, etc?

(If it’s long, please paste to https://ghostbin.com/ and insert the link here.)

Other information