openStream should not be intercepted if Firebase Perf is not initialized

[argzdev]

Proposed fix for #5584:

Issue

Crash happens if a URL connection is opened e.g. url.openStream() when TransportManager has not been initialized.

Investigation

1. openStream in FirebasePerfUrlConnection intercepts all urls that opens connections.
2. openStream requires TransportManager to be initialized
3. 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.

[visumickey]

This change looks good to me.

But this issue needs a more broader look to see if we can capture these network requests as well (may be initialize Transport Manager early). But that is a bigger refactor. So, this change looks good for now.

[argzdev]

PR seems to be failing due to:

• App Distribution release notes needed (not sure why this is being triggered)
• firebase-sessions:test-app:copyRootGoogleServices failing to copy the file which causes the task for :firebase-sessions:test-app:processDebugGoogleServices return a Malformed root json error.