Fix highlight region end column calculation

[charisk]

In a recent PR we took advantage of the parseSarifRegion() from sarif-utils.ts for remote queries. However, parseSarifRegion assumes the region will be used by VS Code tooling (the editor) so it offsets it by 1. This made highlights in the remote queries view miss out on the last character.

Ideally we should be updating parseSarifRegion to be more generic but that would have been a slightly bigger change than I would have liked right now.

Checklist

N/A:

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.