Change the database dump to use SQL instead of binary

[jahow]

The development database dump used in the E2E tests is currently expressed in "compressed" format (440KB).

Because it is a binary file, git cannot do diff and there is no way to prevent someone overwriting the dump with an older version by mistake.

By using SQL format for the dump (which makes the dump 1.8MB large), git should be able to better detect merge conflicts. Git LFS could be used to avoid making the repo to big.