Tests

[MNT] Remove redundant `init`s in `OpenMLTask` descendants by adding ClassVar #2261

Job	Run time
docker	4s
(ubuntu-latest, Py3.8, sk0.23.1, sk-only:false)	3s
(windows-latest, Py, sk0.24.*, sk-only:false)	2s
(ubuntu-latest,Py3.12,sk1.4.*,sk-only:true)	1m 4s
(ubuntu-latest,Py3.10,sk1.6.*,sk-only:true)	58s
(ubuntu-latest,Py3.10,sk1.5.*,sk-only:true)	1m 6s
(ubuntu-latest,Py3.11,sk1.5.*,sk-only:true)	47s
(ubuntu-latest,Py3.11,sk1.6.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.12,sk1.3.*,sk-only:true)	1m 1s
(ubuntu-latest,Py3.11,sk1.7.*,sk-only:true)	1m 4s
(ubuntu-latest,Py3.11,sk1.3.*,sk-only:true)	53s
(ubuntu-latest,Py3.10,sk1.7.*,sk-only:true)	55s
(ubuntu-latest,Py3.13,sk1.6.*,sk-only:true)	1m 5s
(ubuntu-latest,Py3.11,sk1.4.*,sk-only:true)	1m 26s
(ubuntu-latest,Py3.10,sk1.3.*,sk-only:true)	56s
(ubuntu-latest,Py3.13,sk1.5.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.12,sk1.7.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.12,sk1.5.*,sk-only:true)	1m 13s
(ubuntu-latest,Py3.12,sk1.5.*,sk-only:false)	5m 47s
(ubuntu-latest,Py3.12,sk1.6.*,sk-only:true)	1m 12s
(ubuntu-latest,Py3.10,sk1.4.*,sk-only:true)	56s
(ubuntu-latest,Py3.14,sk1.5.*,sk-only:true)	4m 18s
(ubuntu-latest,Py3.12,sk1.5.,pd:2.,sk-only:false)	5m 45s
(windows-latest,Py3.12,sk1.5.*,sk-only:false)	5m 37s
(ubuntu-latest,Py3.14,sk1.7.*,sk-only:false)	5m 45s
(ubuntu-latest,Py3.13,sk1.7.*,sk-only:true)	56s
(ubuntu-latest,Py3.14,sk1.6.*,sk-only:true)	4m 22s
(ubuntu-latest,Py3.14,sk1.7.*,sk-only:true)	1m 5s
	51m 29s

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