Increase Backend.AI Kernel's app startup timeout

[kyujin-cho]

Summary  

• The timeout value should be increased substantially. Determining the ideal value will be controversial, but current setting (5 seconds) is too small.

Steps to Reproduce  

1. Try to start the JupyterLab from NGC Torch 24.09 image on Lablup’s Internal Cloud.

Expected Behavior

• App should start fine

Actual Behavior  

• App does not start - and server returns 500 on start-service

Logs/Errors  

N/A