Microsoft Teams and Slack services produce a Plan output after a successful apply

Starting with the GitLab.com release on March 3rd, 2023, and to be released with %15.10, a successful application of a configuration that includes a gitlab_service_microsoft_teams or a gitlab_service_slack resource will return a non-empty plan. The plan will say that the webhook value (on either resource) is currently "", and the value in the configuration is expected.

Example Configuration that produces a problem:

resource "gitlab_service_slack" "slack" {
  project                      = "${gitlab_project.foo.id}"
  webhook                      = "https://test.com"
}

Test Output:

resource_gitlab_service_slack_test.go:24: Step 1/10 error: Check failed: Check 2/2 error: gitlab_service_slack.slack: Attribute 'webhook' expected "https://test.com", got ""

Prior Description:

There was an issue identified within the nightly acceptance test run, please investigate the issue!

Workflow to tackle this issue:

1. close if it's a duplicate (issues are still created every night).
2. assign yourself if you are investigating this.
3. change labels accordingly.
4. add additional information, start a discussion or provide a fix.

/cc @timofurrer @PatrickRice

Relevant Pipeline

https://gitlab.com/gitlab-org/terraform-provider-gitlab/-/pipelines/795915652