[ENH] remove redundo test

[TonyBagnall]

pointless slow test removed (adds no coverage) as discussed on slack

[aeon-actions-bot]

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I have added the following labels to this PR based on the title: [ $\color{#FEF1BE}{\textsf{enhancement}}$ ].
I would have added the following labels to this PR based on the changes made: [ $\color{#7E0206}{\textsf{regression}}$ ], however some package labels are already present.

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[hadifawaz1999]

thx