Find RMM before CCCL

[wence-]

Description

Since #18235, cudf has not needed CCCL patches. However, that change missed reordering the get_XXX includes, so we have still always been cloning and using a separate CCCL version. Fix that by reordering. We also move the search for RMM before searching for NVTX since an RMM build can also supply that.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[bdice]

Even without patches, the current ordering is still relevant. We want to be able to override CCCL versions for testing purposes, which requires RMM after CCCL. Is there a problem you wanted to solve with this, or is it just an attempt at fixing the comment?

[wence-]

Even without patches, the current ordering is still relevant. We want to be able to override CCCL versions for testing purposes, which requires RMM after CCCL. Is there a problem you wanted to solve with this, or is it just an attempt at fixing the comment?

Fixing the comment. Also, I noticed that a main build of cudf was downloading another (identical) copy of cccl.

Presumably we can still try new versions, but I guess we must remember to change two files, rather than one.

[bdice]

That’s expected behavior (and consistent across RAPIDS) but we can fix the comment so that it doesn’t mention patches. We don’t really want to rely on transitive dependency fetching, because it makes it confusing to override. We’ve had lots of difficulties with that in the past.

[wence-]

/merge