Integration tests are not working

[andygrove]

Describe the bug
I tried running the integration tests and they failed with:

error: failed to load manifest for workspace member `/tmp/ballista/datafusion`

Caused by:
  failed to load manifest for dependency `datafusion-common`

Caused by:
  failed to read `/tmp/ballista/datafusion-common/Cargo.toml`

I assume this is related to the recent refactoring of crates.

To Reproduce
Steps to reproduce the behavior:

./dev/integration-tests.sh

Expected behavior
Test should pass

Additional context
None