ci: remove obsolete upstream project automation

[JOY (JOY)]

Summary

• remove the inactive Project management workflow
• remove its inactive reusable Update project cards for issues dependency
• remove the orphaned Copy issues labels to pull request workflow that targets blockscout/frontend
• preserve release and DOS Docker publishing workflows

Evidence

• all three removed workflows have zero recorded runs
• the repository does not define the required PROJECT_NAME variable
• the repository does not define the required BOT_LABEL_ISSUE_TOKEN secret
• the label workflow hardcodes blockscout/frontend for both label reads and writes
• no internal or public external callers remain after deleting the closed dependency graph

Validation

• git diff --check
• no remaining workflow or documentation references
• actionlint adds no new findings; four unrelated pre-existing findings remain in checks.yml and stale-issues.yml