Export default ENV when PATH is required for command execution

exportfs and authconfig execution was failing with:
No such file or directory - exportfs/authconfig

### References
* `default_env true` documentation: https://docs.chef.io/resources/execute/#properties
* Related issue: sous-chefs/nfs#106

Signed-off-by: Enrico Usai <[email protected]>

cookbooks/aws-parallelcluster-environment/resources/system_authentication/partial/_system_authentication_alinux_centos.rb

@@ -17,6 +17,7 @@
     user 'root'
     # Tell NSS, PAM to use SSSD for system authentication and identity information
     command "authconfig --enablemkhomedir --enablesssdauth --enablesssd --updateall"
+    default_env true
     sensitive true
   end
 end

cookbooks/aws-parallelcluster-environment/resources/system_authentication/partial/_system_authentication_debian.rb

@@ -17,6 +17,7 @@
     user 'root'
     # Enable PAM mkhomedir module
     command "pam-auth-update --enable mkhomedir"
+    default_env true
     sensitive true
   end
 end

cookbooks/aws-parallelcluster-environment/resources/system_authentication/system_authentication_redhat8.rb

@@ -30,6 +30,7 @@
     # authconfig is a compatibility tool, replaced by authselect
     command "authselect select sssd with-mkhomedir"
     sensitive true
+    default_env true
   end unless redhat_on_docker?
 end
 

cookbooks/aws-parallelcluster-environment/resources/volume.rb

@@ -128,5 +128,6 @@
 
   execute "unexport volume" do
     command "exportfs -ra"
+    default_env true
   end
 end