gitlab-ci: fix installing dependencies for fuzz smoke tests

There was a semantic merge conflict between 9cdeb34b (ci: merge scripts which install dependencies, 2024-04-12), which has merged "ci/install-docker-dependencies.sh" into "ci/install-dependencies.sh" and c7b228e0 (gitlab-ci: add smoke test for fuzzers, 2024-04-29), which has added a new fuzz smoke test job that makes use of the now-removed script.

Adapt the job to instead use the new script to install dependencies.