[net processing] Refactor MaybeSendAddr() - early exits

Summary:
Add early exit guard clauses if node.RelayAddrsWithConn() is false or if
current_time < node.m_next_addr_send. Add comments.

This is a backport of core#21236 [5/6]
https://github.com/bitcoin/bitcoin/pull/21236/commits/38c0be5da3af17208b165e73cee7612d3670b038
https://github.com/bitcoin/bitcoin/pull/21236/commits/01a79ff924b11f91796d4aa63c571897b047ac7d

Depends on D10918

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10919