Scan: change exit_code, external_id from int to string

[evilpeach]

Note

Please wait until the CBD has changed the exit_code type.

Implementation details

• Change exit_code and external_id from int to string

Please ensure the following requirements are met before submitting a pull request:

• The pull request is targeted against the correct target branch
• The pull request is linked to an issue with appropriate discussion and an accepted design OR is linked to a spec that describes the work.
• The pull request includes a description of the implementation/work done in detail.
• The pull request includes any and all appropriate unit/integration tests
• You have added a relevant changelog entry to CHANGELOG_UNRELEASED.md
• You have re-reviewed the files affected by the pull request (e.g. using the Files changed tab in the Github PR explorer)

[render]

Your Render PR Server URL is https://d3n-scan-pr-2456.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-bspbuc8ti7j17noel21g.

[pzshine]

LGTM