feat: start with the default postgresql.conf (#149)

Description

Start from a default postgresql.conf always, and apply transformations needed for Database Lab's work.

Related issue

#149 (closed)

Examples

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes, specifications reflect those changes and they have been reviewed OR there are no API changes

Closes #149 (closed)