fix: improve error message in service creation

[lechnerc77]

Purpose

• Fixing error message propagation for service instances
• Adds a generic handling that can be enhanced when future requirements arise
• New test case added to have REST response from service manager
• Closes [BUG] Error Handling during new HANA cloud instance creation #821

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[X] Bugfix
[ ] Feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Test the code via automated test

go test ./...

What to Check

Verify that the following are valid:

• Automated tests are executed successfully

Other Information

n/a

Checklist for reviewer

The following organizational tasks must be completed before merging this PR:

• The PR is assigned to the Terraform project and a status is set (typically "in review").
• The PR has the matching labels assigned to it.
• The PR has a milestone assigned to it.
• If the PR closes an issue, the issue is referenced.
• Possible follow-up items are created and linked.

[lechnerc77]

Successful execution of regression test on local build of provider

[lechnerc77]

• Fixture drift is okay as new test case was recorded and existing have been re-recorded to ensure recorded request structure
• Inclusive language warning is okay as statements come from upstream system that are not managed by us

[vipinvkmenon]

Looks Good