[airgap] there were no VS Code extensions in DS 3.4.0 deployed to airgap OCP 4.12 cluster

Description of problem:

There were problems with installation of VS Code extension in DS 3.4.0.ER-12-20 deployed to x86_64 airgap OCP 4.12 cluster:

• there were no installed extensions
• "Error while fetching extensions, Server returned 503" displayed when search on extension

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

1. deploy DS 3.4.0.ER-12-20 to airgap OCP 4.12.0-rc.5
2. create and open Java Quarkus sample workspace
3. go to extensions view

Actual results:

• there were no installed extensions
• "Error while fetching extensions, Server returned 503" displayed when search on extension
  
  

Expected results:

There are pre-installed extensions displayed.
It is possible to search extenstions

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

Additional info (Such as Logs, Screenshots, etc):

The issue is not reproduced in online OCP 4.10 cluster: