fix: polling service instances (delete)

[lechnerc77]

Purpose

This PR adds the missing polling when deleting a service instance

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

go test ./...

What to Check

Verify that the following are valid

• Test are executed successfully

Other Information

n/a

[lechnerc77]

Test Coverage of new code below 80% (overall coverage estimated after merge 87.3%): missing coverage comes from error branches in destroy that cannot be easily triggered via plugin test framework afaik. As coverage is still above 85% after merge the merge of the PR should be acceptable.

[rui1610]

lgtm.