Add the global span to spawned network init tasks

[teor2345]

Motivation

When I was trying to diagnose a hang bug on crawl_and_dial, it didn't have the global git commit span, so it was hard to work out if it was already fixed by #1709.

Here is what the logs look like before this change:

Feb 17 10:18:59.606  WARN crawl_and_dial: zebra_network::peer_set::set: network request with no peer connections. Hint: check your network connection

Solution

Add the global span to spawned network init tasks

Review

This review is a low priority.

Related Issues

Closes #1575

[teor2345]

Testnet seems unstable right now, affecting CI. That will be fixed by #1222 in the next sprint.

[teor2345]

It looks like we didn't get a fresh merge for CI after #1789, so the testnet sync failed again.

Merging anyway, because #1789 deletes that code, so it can't possibly fail on main.