net: avoid unnecessary GetBindAddress() call
net: avoid unnecessary GetBindAddress() call

Summary:
Our local (bind) address is already saved in `CNode::addrBind` and there
is no need to re-retrieve it again with `GetBindAddress()`.

Also, for I2P connections `CNode::addrBind` would contain our I2P
address, but `GetBindAddress()` would return something like
`127.0.0.1:RANDOM_PORT`.

This is a backport of [[https://github.com/bitcoin/bitcoin/pull/20685 | core#20685]] [7/20]
https://github.com/bitcoin/bitcoin/pull/20685/commits/f6c267db3be2d7077fd2bdbd34860eba838dea99

Depends on D11015

Test Plan: `ninja all check-all`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D11016

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