Change wrapper.filter to wrapper.find in alert_details_table_spec

What does this MR do and why?

To fix Vue3 spec issue around using filter.

References

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• #504670 (closed)

MR acceptance checklist

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Screenshots or screen recordings

No changes.

How to set up and validate locally

$ VUE_VERSION=3 yarn jest spec/frontend/vue_shared/components/alert_details_table_spec.js

Related to #504670 (closed)