gitlab-runner-helper: use default umask

scripts/gitlab-runner-helper sets umask to 0000 to fix issues where ci
jobs would be running as a different user, preventing access to files.

This causes issues when files in repositories end up in build artifacts
with world writable permissions.

One such example is the alpine-gitlab-ci project where `/etc/sudoers.d`
ends up word-writable, preventing sudo to work.

Set it to the standard 0022 to fix this issue.
3 jobs for fix-umask-issue in 25 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #495
docker-alpine s390x
build-s390x

00:00:21

passed #497
docker-alpine x86
build-x86

00:00:21

passed #496
docker-alpine x86_64
build-x86_64

00:00:21