TestExplorer should not be triggering builds using SwiftExecOperation

[adam-fowler]

If the test list fails then a build is triggered. We can't use SwiftExecOperation for builds they can be long operations. Using SwiftExecOperation means you can't see the result of the build, it is a long process you have no control over.

Use this instead

// get buildall task and execute it
const backgroundTask = await getBuildAllTask(this.folderContext);
if (!backgroundTask) {
    return;
}
try {
    await this.folderContext.taskQueue.queueOperation(new TaskOperation(backgroundTask));
} catch {
    // can ignore if running task fails
}