John/refactor integ tests

[jchrostek-dd]

Overview

• Refactoring integ tests so we have a default runtime. For our use case, and at least for now, we don't need to test against multiple runtime version. For instance, Node24 is fine and we don't need to test against Node22, Node20, Node18, etc.
• Fix the local_deploy script. When there are a lot of versions for a lambda layer, it is pulling 2 instead of just 1.
• Update LMI to just deploy 1 instance instead of 3.
• No functional changes.