Fix/ci errors

[werrolf]

Fixes initial composer install to skip (failing) asset setup.
Adds build-bootstrap to prevent app/console fatalities due to missing bootstrap.php.cache, which arise from previous change.
Fixes composer project-name failing on branch names without slash (such as 'master'). This fixes collateral tar errors. Empty project-name output produces an artifact name with a leading dash, which tar complains about as an unknown option.
Removes the repeated second short commit hash from the artifact name. C.f.:

$ echo "$(git describe --tags)-$(git rev-parse --short HEAD)"
v3.0.7.7-14-g3fd1b33-3fd1b33
$ echo "$(git describe --tags HEAD)"
v3.0.7.7-14-g3fd1b33

The short commit hash 3fd1b33 is part of the describe output anyway.