e2e journey prereq step: recent ubuntu use snap

[hokonohara]

Description

Recent ubuntu need snap to install insomnia. The docs mention sudo apt-get install insomnia

Acceptance Criteria

Add a note for recent ubuntu. The command line will be

sudo snap install insomnia

Additional Information

docs link
https://eclipse-tractusx.github.io/docs/tutorials/e2e/prerequisites/#install-insomnia