Clean up unused environments in CI freestyle jobs

[yanavasileva]

Acceptance Criteria (Required on creation)

After migration to Jenkins declarative pipelines in 7.15 there are several freestyle jobs that remained. Those jobs don't use most of the environments that we support but we still carry them after we copied the jobs during the minor release.

• In scope of 7.19 and 7.20 freestyle jobs
• Remove as much as possible environment variables that are not used by the freestyle jobs
• Evaluate which tests to adjust or remove depending on the effort
• Invest minimal possible effort

Hints

Links

• Follow up of https://github.com/camunda/camunda-bpm-platform/issues/2936 and https://github.com/camunda/jenkins-job-dsl-seed-jobs/pull/391

Breakdown

Dev2QA handover

• [ ] Does this ticket need a QA test and the testing goals are not clear from the description? Add a Dev2QA handover comment

[yanavasileva]

In review with Infra