Revert "math/hs-Agda: Disable building emacs mode files until upstream fixes it"

This reverts commit e1197b1e58b2cdb5f98b4fd00db2e340800b444f.

Upstream bug [0] was fixed/closed 2025-03-28

[0] https://github.com/agda/agda/issues/7730

PR: 288578
Approved by: alven (maintainer, with haskell@ hat)
Approved by: yuri (Mentor)