[Backport 7.71.x] omnibus: secret-gen-connector: ensure the output dir exists (#41972)

Backport 73e7543 from #41864.

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### What does this PR do?

Ensure the `secret-generic-connector` destination folder exists

### Motivation

When leveraging omnibus build cache for earlier dependencies, there is
no guaranty that the folder exists, which caused a handful of build
failures

### Describe how you validated your changes

### Additional Notes

Co-authored-by: Hugo Beauzée-Luyssen <[email protected]>

Author: dd-octo-sts[bot]

omnibus/config/software/secret-generic-connector.rb

@@ -74,6 +74,7 @@
   license_file "https://raw.githubusercontent.com/DataDog/datadog-secret-backend/master/LICENSE"
 
   if windows?
+    mkdir "#{install_dir}/bin/agent"
     # Extract the zip file
     copy "#{project_dir}/datadog-secret-backend.exe", "#{install_dir}/bin/agent/secret-generic-connector.exe"
   else