PYTHON-5781 Increase code coverage for network_layer.py #9310

Job	Run time
Link Check	2m 37s
static	1m 59s
DocTest	1m 3s
Docs Checks	34s
CPython 3.13t-ubuntu-latest	13m 10s
CPython pypy-3.11-ubuntu-latest	14m 4s
CPython 3.10-ubuntu-latest	12m 55s
Make an sdist	19s
Typing Tests (3.11)	50s
Typing Tests (3.10)	48s
Test minimum dependencies and Python	1m 0s
Coverage	13m 37s
Integration Tests	51s
Install from SDist and Test	1m 10s
	1h 4m 57s

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