Add privacy notice to pr and issue templates (#11)

* Add privacy notice to templates

Files modified:
- .github/ISSUE_TEMPLATE/bug.md
- .github/ISSUE_TEMPLATE/bug_report.md
- .github/ISSUE_TEMPLATE/enhancement_request.md
- .github/ISSUE_TEMPLATE/feature.md
- .github/ISSUE_TEMPLATE/flaking-test.md
- .github/pull_request_template.md

* Drop duplicate templates: `bug_report.md` is duplicate of `bug.md`, `enhancement_request.md` of `feature.md`

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Co-authored-by: Martin Weindel <martin.weindel@sap.com>

Author: RaphaelVogel