Fix retried builds icon sprite to use css_class

What does this MR do?

We have replaced the fa-warning icons, however in the retried builds there is one using class: instead of css_class: which causes errors because class: doesn't exist as an attribute, this updates it to css_class instead.

Related to #276495 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

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