Remove unnecessary directory existing check

Author: Takahiro-Yoko

modules/exploits/linux/local/cve_2023_0386_overlayfs_priv_esc.rb

@@ -112,10 +112,6 @@ def exploit
     # Upload exploit executable
     exploit_dir = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
 
-    if file_exist?(exploit_dir)
-      fail_with(Failure::BadConfig, 'Exploit dir already exists')
-    end
-
     mkdir(exploit_dir)
     register_dir_for_cleanup(exploit_dir)