fix: Use control-group KillMode in systemd config

[dpaasman00]

Proposed Change

Need to use the value control-group for KillMode in the systemd service config. Linear ticket.

Testing:

• Checkout this branch and run make clean, make install-tools, and make release-test
• Get the relevant linux package (.rpm or .deb) on to your linux machine, as well as the script at scripts/install/install_unix.sh
• Run the script on the linux machine with sudo ./install_unix.sh -f <path-to-linux-pkg> ... followed by the remaining argument flags to connect to a bindplane instance like -e and -s. Do not provide a version using -v
• Roll a config out to the agent
• Run systemctl status bindplane-otel-collector.service to see the collector and supervisor running
• Stop the service with systemctl stop bindplane-otel-collector.service and rerun the status command to verify the collector is stopped

Checklist

• Changes are tested
• CI has passed