Revert "workflows/release-binaries: Disable flang on Darwin (#164667)" (#216667)
This reverts commit 6d54a5e5b83ce3502b7a3488fea5afe1c8bf9c5c.
Flang Darwin builds were reverted due to #160546. That issue has not
been reproducible (at least on my machine) for several months. There was
a request for MacOS builds on the most recent flang community call.
Flang is not enabled in the MacOS pre-commit CI.
Closes #160546