Tests

[MNT] Remove redundant `init`s in `OpenMLTask` descendants by adding ClassVar #1743

Job	Run time
docker	3s
(windows-latest, Py, sk0.24.*, sk-only:false)	4s
(ubuntu-latest, Py3.8, sk0.23.1, sk-only:false)	4s
(ubuntu-latest,Py3.11,sk1.3.*,sk-only:true)	56s
(ubuntu-latest,Py3.10,sk1.7.*,sk-only:true)	58s
(ubuntu-latest,Py3.10,sk1.3.*,sk-only:true)	55s
(ubuntu-latest,Py3.10,sk1.4.*,sk-only:true)	57s
(ubuntu-latest,Py3.12,sk1.4.*,sk-only:true)	58s
(ubuntu-latest,Py3.12,sk1.3.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.10,sk1.5.*,sk-only:true)	58s
(ubuntu-latest,Py3.10,sk1.6.*,sk-only:true)	1m 1s
(ubuntu-latest,Py3.11,sk1.4.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.11,sk1.6.*,sk-only:true)	54s
(ubuntu-latest,Py3.13,sk1.7.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.13,sk1.5.*,sk-only:true)	1m 2s
(ubuntu-latest,Py3.12,sk1.5.*,sk-only:true)	1m 1s
(ubuntu-latest,Py3.14,sk1.7.*,sk-only:false)	1h 6m 48s
(ubuntu-latest,Py3.11,sk1.7.*,sk-only:true)	1m 5s
(ubuntu-latest,Py3.12,sk1.7.*,sk-only:true)	1m 2s
(ubuntu-latest,Py3.12,sk1.5.*,sk-only:false)	52m 43s
(ubuntu-latest,Py3.14,sk1.5.*,sk-only:true)	4m 14s
(ubuntu-latest,Py3.11,sk1.5.*,sk-only:true)	57s
(ubuntu-latest,Py3.14,sk1.7.*,sk-only:true)	1m 10s
(ubuntu-latest,Py3.14,sk1.6.*,sk-only:true)	4m 19s
(ubuntu-latest,Py3.13,sk1.6.*,sk-only:true)	1m 8s
(windows-latest,Py3.12,sk1.5.*,sk-only:false)	6h 0m 8s
(ubuntu-latest,Py3.12,sk1.6.*,sk-only:true)	1m 10s
	8h 27m 44s

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