chore: ignore vendor-bin for coverage

[kesselb]

Summary

• Otherwise the coverage for *.php files in vendor-bin is also calculated.
• Fix Error: The "--coverage-clover" option does not exist. for the external generic workflow.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[nickvergessen]

🙈

[come-nc]

Where does one see the coverage data?

[kesselb]

It's uploaded to: https://app.codecov.io/gh/nextcloud/server

• Uploading was broken for some days due to a change in the codecov action.
• The "raw" data can be viewed for each commit. For example: https://app.codecov.io/gh/nextcloud/server/commit/36d6b0f1e6eae58e20f35bb9d87671d338ea0a61