Split integration test file

[emily-emily]

Problem

Currently all of our integration tests are included in a single file, making it hard to navigate and read.

Solution

This PR splits the integration tests into multiple files: common.rs for common helper code (eg. generate index name), and two files for control plane and data plane integration tests.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Infrastructure change (CI configs, etc)
• Non-code change (docs, etc)
• None of the above: (explain here)

Test Plan

All existing test cases pass

[ssmith-pc]

I did not review in detail, but I trust that you know what you're doing here