[NVIDIA-IMEX] Removing flush cache as it does not exist for package resource

Author: Himani Anil Deshpande

cookbooks/aws-parallelcluster-platform/resources/nvidia_imex/partial/_nvidia_imex_common.rb

@@ -51,7 +51,6 @@
   package "nvidia-imex-#{_nvidia_imex_version}" do
     retries 3
     retry_delay 5
-    flush_cache({ before: true })
     # version _nvidia_imex_version
   end
 end