Fix failing test in legacy opmath

[astralcai]

A follow up of https://github.com/PennyLaneAI/pennylane/pull/6252, does the same but with a different test.

[github-actions[bot]]

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.59%. Comparing base (060bb9a) to head (9e09e84). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #6272 +/- ## ======================================= Coverage 99.59% 99.59% ======================================= Files 444 444 Lines 42321 42321 ======================================= Hits 42149 42149 Misses 172 172 ```

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