Revert "Set boot.loader.grub.configurationLimit to 1 for gce/azure/amazon images. Setting to 0 results in empty grub config."

The issue was that grub was not building the default entry which would
leave systems unbootable. This can now be safely reverted as the default
entry is being built once again.

This reverts commit fd1fb0403c.

nixos/modules/virtualisation/amazon-image.nix

@@ -170,7 +170,7 @@ in
 
     # Don't put old configurations in the GRUB menu.  The user has no
     # way to select them anyway.
-    boot.loader.grub.configurationLimit = 1;
+    boot.loader.grub.configurationLimit = 0;
 
     # Allow root logins only using the SSH key that the user specified
     # at instance creation time.

nixos/modules/virtualisation/azure-common.nix

@@ -14,7 +14,7 @@ with lib;
 
   # Don't put old configurations in the GRUB menu.  The user has no
   # way to select them anyway.
-  boot.loader.grub.configurationLimit = 1;
+  boot.loader.grub.configurationLimit = 0;
 
   fileSystems."/".device = "/dev/disk/by-label/nixos";
 

nixos/modules/virtualisation/google-compute-image.nix

@@ -106,7 +106,7 @@ in
 
   # Don't put old configurations in the GRUB menu.  The user has no
   # way to select them anyway.
-  boot.loader.grub.configurationLimit = 1;
+  boot.loader.grub.configurationLimit = 0;
 
   # Allow root logins only using the SSH key that the user specified
   # at instance creation time.