Deploy to container app from Container Registry wizard exits instead of returning to selection step when cancelling .env file browser

[v-amyang]

OS: Win 11
Build Version: 20260129.1
Regression: Not a Regression

Repro Steps:

1. Right click Container Apps->Select ‘Deploy image to container app’
2. When prompted with Selecting a .env file to set the environment variables for the container instance, choose Browse…
3. The system file picker dialog opens->Click 'Cancel' in the file picker dialog

Expect:
Clicking Cancel in the file picker should close the file picker only and return the user to the previous selection UI (Browse… / Skip for now)

Actual:
Deploy wizard exits immediately, user is not returned to the previous step, so deployment flow must be restarted from the beginning