test(math): fix FormatDec test

[julienrbrt]

Description

Closes: #15214

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[facundomedica]

LGTM, agree that it was weird to be importing test data from another package. Also, it didn't show up in the tests in the other PR 🤔

[julienrbrt]

LGTM, agree that it was weird to be importing test data from another package. Also, it didn't show up in the tests in the other PR thinking

Yeah, because CI runs only tests on per diff in a package, which makes sense when not doing importing testdata from somewhere else.
Checked the repo, and it does not happen anywhere else.