E2E: disable sdnotify for Consul agents (#26078)

In our E2E environment we've seen some flakiness with the Consul-related
tests. As it turns out, the Consul agents are getting restarted every 90s or so
because they're timing out their systemd notification.

> consul.service: start operation timed out. Terminating.

This appears to be a known issue in Consul and we'll try to contribute some help
to hunt down the cause if they want help, but in the meantime let's remove it
from our systemd unit files for the Consul agents.

Ref: https://github.com/hashicorp/consul/issues/16844#issuecomment-1913282248

e2e/terraform/packer/ubuntu-jammy-amd64/consul.service

@@ -6,11 +6,12 @@ After=network-online.target
 [Service]
 Restart=on-failure
 Environment=CONSUL_ALLOW_PRIVILEGED_PORTS=true
-ExecStart=/usr/local/bin/consul agent -config-dir="/etc/consul.d"
+WorkingDirectory=/etc/consul.d
+ExecStart=/usr/bin/consul agent -config-dir="/etc/consul.d"
 ExecReload=/bin/kill -HUP $MAINPID
 KillSignal=SIGTERM
-User=root
-Group=root
+User=consul
+Group=consul
 
 [Install]
 WantedBy=multi-user.target

e2e/terraform/provision-infra/provision-nomad/etc/consul.d/consul.service

@@ -4,7 +4,6 @@ Requires=network-online.target
 After=network-online.target
 
 [Service]
-Type=notify
 Restart=on-failure
 Environment=CONSUL_ALLOW_PRIVILEGED_PORTS=true
 WorkingDirectory=/etc/consul.d