Revert "Disable OSX10.14 Helix jobs for now (#36500)" (#36563)
Revert "Disable OSX10.14 Helix jobs for now (#36500)" (#36563)

This reverts commit 6f1b2cda6d4b81dbb8c924eaeef64d6604ff67bd.
aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore