make almost all scripts use bash and set euo pipefail

.gitlab-ci.yml

maint/binary_size

maint/changed_crates

maint/check_licenses

maint/coverage

maint/coverage_fuzz_corpora

maint/docker_reproducible_build

maint/downgrade_dependencies

maint/fuzz_it_all

maint/hooks/pre-commit

maint/hooks/pre-push

maint/readmes

maint/reproducible_build

maint/shellcheck_all

maint/with_coverage

tests/chutney/setup

tests/chutney/teardown

tests/chutney/test