Add dask-expr to dask conda recipe

[charlesbluca]

Closes #8574
Supersedes #8575

• Tests added / passed
• Passes pre-commit run --all-files

[github-actions]

Unit Test Results

See test report for an extended history of previous test failures. This is useful for diagnosing flaky tests.

    29 files  ± 0      29 suites  ±0   11h 9m 10s ⏱️ + 9m 57s
 4 058 tests ± 0   3 947 ✅  -  2    109 💤 ±0  2 ❌ +2 
54 930 runs  +18  52 521 ✅ +21  2 407 💤  - 5  2 ❌ +2 

For more details on these failures, see this check.

Results for commit b9793d2. ± Comparison against base commit 3f77d1b.

♻️ This comment has been updated with latest results.

[rjzamora]

@charlesbluca - Just checking in: Is this blocked by any legitimate CI failures?

[charlesbluca]

Nope, think this is all just flaky CI - the core job impacted here is the conda build which should be unblocked by this

[quasiben]

Thanks @charlesbluca @rjzamora . As this changes conda yml we should give @jrbourbeau and/or @fjetter some time to review. I'll tentatively plan to merge after the release of 2024.4.1
xref: dask/community#370

[quasiben]

With the release done and dask/dask#11014 merged in. I'll merge this when CI finishes. Looking green so far...

[quasiben]

I think we can ignore the codecov failure here as this PR touches no code. We suspect this is an issue with uploaded base vs head. Merging in