Align commands to install composer dependencies

Currently we use the following composer commands to install dependencies: (state from commit https://github.com/ecamp/ecamp3/commit/2bb7b845901260e00b7e7b6ceca053c496eb3b3b)
```
Unclassified
ecamp3
.github/workflows
continuous-integration-optional.yml
- run: composer install --no-interaction --no-plugins --no-scripts --prefer-dist
- run: composer install --no-interaction --no-plugins --no-scripts --prefer-dist
- run: composer install --prefer-dist --no-progress --no-interaction
continuous-integration.yml
- run: composer install --no-interaction --no-plugins --no-scripts --prefer-dist
- run: composer install --prefer-dist --no-progress --no-interaction
api
Dockerfile
composer install --prefer-dist --no-dev --no-autoloader --no-scripts --no-progress; \
api/docker/php
docker-entrypoint.sh
composer install --prefer-dist --no-progress --no-interaction
```
This caused not all ci steps to fail: #3399

This seems a little random, so i suppose we make concept were we define where which of the following flags is appropriate
- --no-dev (i assume when we build for production)
- --no-autoloader (i assume in the dockerfile, but maybe we want to generate the autoload classes and build time to have faster container startup)
- --no-plugins
- --no-scripts
- --prefer-dist (everywhere)

Compare the Composer commands in .github/workflows/continuous-integration-optional.yml, .github/workflows/continuous-integration.yml, api/Dockerfile, and api/docker/php/docker-entrypoint.sh, starting with the failure reported in #3399. Define which flags belong in CI, production builds, and container startup, then verify that the relevant CI steps pass with consistent commands.

Written by the indexing model from the issue text.