Disable Slurm database bootstrap from external slurmdbd

The external slurmdbd instance cannot use Slurm client commands
since it does not have a "full configuration source" (it's
outside a Slurm cluster).

This must be investigated with SchedMD.

Signed-off-by: Jacopo De Amicis <jdamicis@amazon.it>

cookbooks/aws-parallelcluster-slurm/recipes/config/config_slurm_accounting.rb

@@ -77,7 +77,7 @@
   command "#{node['cluster']['slurm']['install_dir']}/bin/sacctmgr show clusters -Pn"
   retries node['cluster']['slurmdbd_response_retries']
   retry_delay 10
-end unless on_docker?
+end unless on_docker? || node['is_external_slurmdbd']
 
 bash "bootstrap slurm database" do
   user 'root'
@@ -108,4 +108,4 @@
     # This is not important for the scope of this script, so we return 0.
     exit 0
   BOOTSTRAP
-end unless on_docker?
+end unless on_docker? || node['is_external_slurmdbd']