maintainers/scripts/haskell: make commit messages more consistent

Make sure they are all prefixed with haskellPackages: except for
update-hackage.sh which changes the top-level attribute
all-cabal-hashes.

maintainers/scripts/haskell/update-stackage.sh

@@ -61,7 +61,7 @@ sed -r \
 if [[ "${1:-}" == "--do-commit" ]]; then
 git add $stackage_config
 git commit -F - << EOF
-Stackage Nightly: $old_version -> $version
+haskellPackages: stackage-nightly $old_version -> $version
 
 This commit has been generated by maintainers/scripts/haskell/update-stackage.sh
 EOF