files.partcipants.timeout doesn't handle the undefined case

[lramos15]

As part of my work for #125422 I discovered that const timeout = this.configurationService.getValue<number>('files.participants.timeout'); expects a number but at least in the test cases this value is undefined. Adding the below type safety code leads to many working copy tests failing.

if (typeof timeout !== 'number') {
  return;
}