Use haddock3 install which comes with cns executable

[sverhoeven]

Follow up on haddocking/haddock3#1013

Deployment now with one command less

git clone https://github.com/i-VRESSE/haddock3-webapp .
cd deploy/arq
docker compose -f deploy/arq/docker-compose.yml up

To test this PR you should use

git clone https://github.com/i-VRESSE/haddock3-webapp .
git switch haddock3-easy-install
cd deploy/arq
WEBAPP_TAG=haddock3-easy-install docker compose -f deploy/arq/docker-compose.yml up --pull always

[github-actions]

Please delete the images belonging to this Pull Request as they are no longer useful.

• ghcr.io/i-vresse/haddock3-webapp
• ghcr.io/i-vresse/bartender
• ghcr.io/i-vresse/certmaker

Goto versions page of each image, find version called pr-154, filter on tagged versions by clicking "N tagged" button in table header, click on ... button and select Delete version.