default subnetwork doesn't appear when creating a new runtime template

[nyoungstudios]

Steps

• Click "New Runtime Template" from the Launcher
• looking at the "Network Configuration" - the "Primary network" and "Subnetwork" both say default. And clicking on the subnetwork drop down menu shows this image
  
• Clicking the primary network drop down menu and then selecting a different primary network
• Then clicking the primary network drop down menu and selecting the "default" primary network again now shows the correct default subnetwork (default-123456...).
• Additionally, now clicking the subnetwork drop down menu shows a list of the other available subnetworks

Expected behavior

• The default subnetwork should be prepopulated upon opening the runtime template config rather than having to change the primary network value back and forth to get to the correct subnetwork value

Environment

# OS
Ubuntu 20.04 LTS x86_64

# Python version
Python 3.10.13

# Relevant Python dependencies
jupyterlab==4.0.6
dataproc_jupyter_plugin==0.1.9

# output of gcloud version
Google Cloud SDK 448.0.0
beta 2023.09.22
bq 2.0.98
bundled-python3-unix 3.9.16
core 2023.09.22
gsutil 5.25