Release v2.20.2 removed crash_report_issue_title,
crash_report_body_template and crash_report_body_paste from the base
strings.xml, but values-be still carried its translations of them.
check_translations.py fails on stale keys, and since translations.yaml
runs on every PR with no path filter, the required "Translations / check"
status has been red for every pull request opened since that release.
There is nothing left for these to translate, so remove them.