PYTHON-5544 Revert changes to base protocol layer #8173

Job	Run time
DocTest	1m 13s
static	7m 9s
CPython 3.13t-ubuntu-latest	11m 34s
CPython 3.9-ubuntu-latest	11m 30s
Test async's minimum dependencies and Python	48s
Link Check	2m 35s
CPython pypy-3.10-ubuntu-latest	12m 38s
Docs Checks	47s
Make an sdist	17s
Typing Tests (3.9)	1m 0s
Typing Tests (3.11)	59s
Test using minimum dependencies and supported Python	38s
Install from SDist and Test	1m 0s
	52m 8s

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