openStream should not be intercepted if Firebase Perf is not initiali…

…zed (#5885)

Proposed fix for #5584:

### Issue
Crash happens if a URL connection is opened e.g. `url.openStream()` when
`TransportManager` has not been initialized. If developer wants to
programmatically enable Firebase using FirebaseOptions, but have
included the Firebase Perf plugin, the app will crash after doing a
network call.

### Steps to reproduce
1. Add Firebase perf plugin
- Module `build.gradle`
```
plugins {
    alias(libs.plugins.android.application) apply false
    alias(libs.plugins.jetbrains.kotlin.android) apply false
    id("com.google.gms.google-services") version "4.4.1" apply false
    id("com.google.firebase.firebase-perf") version "1.4.2" apply false
}
```
- App `build.gradle`
```
plugins {
    alias(libs.plugins.android.application)
    alias(libs.plugins.jetbrains.kotlin.android)
    id("com.google.gms.google-services")
    id("com.google.firebase.firebase-perf")
}
```
2. Disable Firebase
```xml
        <provider
            android:name="com.google.firebase.provider.FirebaseInitProvider"
            android:authorities="${applicationId}.firebaseinitprovider"
            tools:node="remove"
            />   
```
3. Do a network call
```
val url = URL("https", "www.amazon.com", 443, "")
val inputStream = url.openStream()
```

### Investigation
1. `openStream` in `FirebasePerfUrlConnection` intercepts all urls that
opens connections.
5. `openStream` requires `TransportManager` to be initialized
6. `TransportManager` is only initialized after `FirebasePerformance`
has been initialized

### Solution
If `TransportManager` is not initialized, we should simply return the
URL openStream and not intercept the connection.

firebase-perf/CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
-
+[fixed] Fixed an `ExceptionInInitializerError` where the `url.openStream()` causes a crash if
+FirebasePerf is not yet initialized.
 
 # 20.5.2
 * [changed] Bump internal dependencies.

firebase-perf/src/main/java/com/google/firebase/perf/network/FirebasePerfUrlConnection.java

@@ -58,6 +58,9 @@ public static InputStream openStream(final URL url) throws IOException {
    */
   static InputStream openStream(URLWrapper wrapper, TransportManager transportManager, Timer timer)
       throws IOException {
+    if (!TransportManager.getInstance().isInitialized()) {
+      return wrapper.openConnection().getInputStream();
+    }
     timer.reset();
     long startTime = timer.getMicros();
     NetworkRequestMetricBuilder builder = NetworkRequestMetricBuilder.builder(transportManager);