debug: activate auto launch onStartupFinished (#164481)
debug: activate auto launch onStartupFinished (#164481)

For https://github.com/microsoft/vscode-internalbacklog/issues/3209

We still need to activate it for every workspace, but since Daniel's
improvements to environment variable application a few months ago, using
onStartupFinished should be pretty safe and seamless.
microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode