fix: issue a checkpoint after successful execution of query preprocessing scripts

Description

The query preprocessing scripts on the snapshot stage may contain queries that significantly change the contents of the database. However, the checkpoint does not occur after that, because it was performed at the previous stage as a part of the standard workflow.

This means that the clone provisioning time may increase and exceed the startup timeout.

To avoid this make an automatic checkpoint as part of the standard processing.

Related issue

Thread in the DLE Community Slack: https://database-lab-team.slack.com/archives/CTETNN484/p1688723935474389?thread_ts=1687876182.901579&cid=CTETNN484

Examples

Checklist

• MR description has been reviewed
• MR changes are functionally tested
• MR does NOT have API/CLI changes OR there are API/CLI changes and they have been reviewed & DOCS ARE ADJUSTED (reference doc, etc)
• MR does NOT have UI changes OR there are UI changes and they have been reviewed & UX IS REVIEWED