MM-57532: Improve timeouts for some tests (#26642)

- Bump timeouts for some cases
- Improve sleep with require/assert.EventuallyT
for better performance and reliability.

https://mattermost.atlassian.net/browse/MM-57532

```release-note
NONE
```

server/channels/app/platform/web_hub_test.go

@@ -190,7 +190,7 @@ func TestHubSessionRevokeRace(t *testing.T) {
 
 	done := make(chan bool)
 
-	time.Sleep(time.Second)
+	time.Sleep(2 * time.Second)
 	// We override the LastActivityAt which happens in NewWebConn.
 	// This is needed to call RevokeSessionById which triggers the race.
 	th.Service.AddSessionToCache(sess1)