refactor(accounts-controller): use type-cast instead of @ts-expect-error

[ccharly]

Explanation

Commenting out the @ts-expect-error was not very reliable sometimes (it works everytime on the CI, but not everytime when compiling/running tests locally). We sometimes have to uncomment the directive to run the tests (which is a bit annoying and force you to have some "unstaged change" in git).

The type-cast does get rid of the compile-error with WritableDraft while still providing the same "object signature" and has 0 impact at runtime either. So this is safe.

References

N/A

Changelog

N/A

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes