RFR: 1603: Make labels handling consistent in all Issue implementations

[Zhao Song]

On Tue, 4 Oct 2022 17:01:15 GMT, Zhao Song <duke at openjdk.org> wrote:

>> I think we update the internal labels in GitHubPullRequest and GitHubMergeRequest because we could get the return value of the update request. However, for Jira Issue, I read the document of Jira REST API, it shows that it wouldn't have return value of the update request, it will just return Status 204.
>> Reference:
>> https://developer.atlassian.com/server/jira/platform/jira-rest-api-examples/
>
> So we update the internal labels in GitHubPullRequest and GitLabMergeRequest could help us reduce one request. But update the internal labels here, I think we wouldn't get any benefit.

NVM, my bad, update here would also reduce one request, I will change it

-------------

PR: https://git.openjdk.org/skara/pull/1387