Duplicate commit status entries created during validation

When investigating an issue, I noticed that there are duplicates for commits that have been submitted multiple times to the API. We need to properly update existing entries as this will lead to a much faster inflation of commit count and could impact performance. An example of this in the wild is https://api.eclipse.org/git/eca/status/2d3173d62295ec0d871494c2ad6f2fd8/ui