Fix output of elapsed time in section markers in gitlab

[bk-tba]

According to this https://docs.gitlab.com/ee/ci/jobs/#custom-collapsible-section, we need to provide a unix timestamp in seconds, not in milliseconds.

This is a reduced raw output of a deployer-job i just ran:

�[32;1mSkipping Git submodules setup�[0;m
section_end:1691389375:get_sources
�[0Ksection_start:1691389375:download_artifacts
�[0K�[0K�[36;1mDownloading artifacts�[0;m�[0;m
�[32;1mDownloading artifacts for build_release_frontend (431863)...�[0;m
...
section_end:1691389376:download_artifacts
[...]
�[0Ksection_start:1691389377467:1691389377467[collapsed=true]
�[0Kdeploy:setup
�[0Ksection_end:1691389379794:1691389377467
�[0K

As you can see, the output generated by gitlab itself has 10-digit-timestamps, but the output generated by deployer is based on millis. This leads to misleading runtimes:

All of this actions took less than a few secongs but being displayed as various minutes.