Use setTimeout instead of microtask to delay Concast cancellation.

Inspired by @cornedor's comment:
#7608 (comment)

Should help with some instances of issue #7608, specifically those with
global unhandled promise rejection errors. I don't know if this is the
full solution, but I believe it is helpful and safe to introduce a delay
before unsubscribing, giving other subscribers a chance to subscribe,
thereby saving the Concast from needing to be cancelled.

src/core/QueryManager.ts

@@ -1127,9 +1127,8 @@ export class QueryManager<TStore> {
     // This cancel function needs to be set before the concast is created,
     // in case concast creation synchronously cancels the request.
     this.fetchCancelFns.set(queryId, reason => {
-      // Delaying the cancellation using a Promise ensures that the
-      // concast variable has been initialized.
-      Promise.resolve().then(() => concast.cancel(reason));
+      // This delay ensures the concast variable has been initialized.
+      setTimeout(() => concast.cancel(reason), 10);
     });
 
     // A Concast<T> can be created either from an Iterable<Observable<T>>

src/utilities/observables/Concast.ts

@@ -178,7 +178,7 @@ export class Concast<T> extends Observable<T> {
         // Delay unsubscribing from the underlying subscription slightly,
         // so that immediately subscribing another observer can keep the
         // subscription active.
-        if (sub) Promise.resolve().then(() => sub.unsubscribe());
+        if (sub) setTimeout(() => sub.unsubscribe(), 10);
         this.sub = null;
         this.latest = ["error", error];
         this.reject(error);