Move integration tests to integration package

[pietern]

Changes

Objectives:

• A dedicated directory for integration tests
• It is not picked up by go test ./...
• No need for a TestAcc test name prefix
• More granular packages to improve test selection (future)

The tree structure generally mirrors the source code tree structure.

Requirements for new files in this directory:

• Every package must be named after its directory with _test appended
  • Requiring a different package name for integration tests avoids aliasing with the main package.
• Every integration test package must include a main_test.go file.

These requirements are enforced by a unit test in the integration package.

Tests

Integration tests pass.

The total run time regresses by about 10%. A follow-up change that increases the degree of test parallelism will address this.

[denik]

nit: I find "internal" not very descriptive. "helpers" or "utils" or "setuputil" would be better.

[pietern]

I can move it to a package inside internal. We do need the internal nesting because it means it can only be imported by other packages inside integration. See https://go.dev/doc/go1.4#internalpackages

[github-actions]

If integration tests don't run automatically, an authorized user can run them manually by following the instructions below:

Trigger:
go/deco-tests-run/cli

Inputs:

• PR number: 2009
• Commit SHA: da2d3fdda4da9960686fed0cb1ba0c2b16153c06

Checks will be approved automatically on success.

[eng-dev-ecosystem-bot]

Test Details: go/deco-tests/12317614117

[pietern]

One additional test skip in the last commit. Merging without waiting for another integration test run.