debug: make serverReadyAction multi-session aware
debug: make serverReadyAction multi-session aware

Fixes #109171

microsoft/vscode,microsoft/vscode,eamodio/vscode,eamodio/vscode,microsoft/vscode,eamodio/vscode,eamodio/vscode,eamodio/vscode,microsoft/vscode,eamodio/vscode,eamodio/vscode,microsoft/vscode,eamodio/vscode,microsoft/vscode,eamodio/vscode,eamodio/vscode,eamodio/vscode,microsoft/vscode,microsoft/vscode,eamodio/vscode,eamodio/vscode,eamodio/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,eamodio/vscode,microsoft/vscode,eamodio/vscode,microsoft/vscode,microsoft/vscode,eamodio/vscode,microsoft/vscode,microsoft/vscode