Not meaningful timeout default values leading to hanging requests

[TheRittler]

[REQUIRED] Step 2: Describe your environment

• Operating System version: MacOS Sonoma 14.1.1
• Firebase SDK version: v9.2.0
• Library version: _____
• Firebase Product: Firebase Cloud Messaging

[REQUIRED] Step 3: Describe the problem

Sometimes the Google Server do not respond (like described in #850 ). However, the default values to read timeout and connect timeout are "0" because they are default initialized with 0 in the FirebaseOptions. So these requests hang for infinite time.

Steps to reproduce:

Send a message via FCM and the SDK. If Google does not respond, there is not timeout.

Fix:

Provide meaningful default values like 20s. This is the default in the Google HTTP Client (com.google.api.client.http.HttpRequest#readTimeout).

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.