Fix ownership issue in Debian packages

Removed

• Drop support for Debian Jessie and Debian Stretch for the stand-alone agent packages.

Fixed

• Ensure adduser dependency is declared as such on the Debian package.

This fixes an issue in certain environments, such as in Ubuntu Noble container images, where the appsignal-agent user fails to be created during installation because the adduser and addgroup command-line utilities are not present by default.

• Fix file ownership issue on stand-alone Debian packages. Ensure that the /etc/appsignal-agent.conf configuration file is owned by the appsignal-agent user.

• Fix a performance issue when sanitising INSERT INTO ... VALUES queries.

This release can be installed through our standalone agent packages and as a Docker image.