chore: update k3s_create.sh to allow third organization

[ThibaultFy]

Description

Propose a Skaffold profile to create 3 orgs in standalone mode. This profile is called "three_orgs".

How has this been tested?

CI + Locally

Companion

• https://github.com/Substra/substra-backend/pull/733
• https://github.com/Substra/orchestrator/pull/280
• https://github.com/Substra/substra-documentation/pull/365