[SIGMON-445] min pic timestamp

Context

• task: https://its.cern.ch/jira/browse/SIGMON-445
• lhc-sm-api merge request: lhc-sm-api!226 (closed)
• lhc-sm-notebook merge request: lhc-sm-notebook!32 (closed)
• lhc-sm-pic merge request: https://gitlab.cern.ch/LHCData/lhc-sm-analysis/lhc-sm-pic/-/merge_requests/10

What was done

• the notebook use pic analysis from lhc-sm-pic. The 'first_timestamp_pic' is registered as a partial result by the analysis class, hence no need for sort(list_with_timestamps)[0]
• Useless 'import prints' were removed

TODO

• ?

QA

• no sonar
• no unit tests
• the references for the acceptance tests were updated

Review objectives

• ?