Fix gsi artifact

Description

GSI artifact were not saved

Issue(s)

https://gitlab.e.foundation/e/backlog/-/issues/4951

Test procedures

create a new pipeline on https://gitlab.e.foundation/e/priv/os/build/-/pipelines/new

with priv/os/build branch: fix-gsi

DEVICE: treble_a64_avN

check if an artifact is available

this is my result:

https://gitlab.e.foundation/e/priv/os/build/-/pipelines/165166

Technical details

BACKUP_INTERMEDIATE_SYSTEM_IMG needs to be done outside of the loop when no e-*zip is generated

Check list

• Self review
• Test procedure explained