remove `keyfile` from `_connection_keys` #15313

Job	Run time
unit test / python 3.8	1m 17s
build packages	18s
unit test / python 3.9	1m 14s
code-quality	1m 22s
unit test / python 3.10	1m 20s
unit test / python 3.11	1m 11s
verify packages / python 3.8 / ubuntu-latest	34s
verify packages / python 3.9 / ubuntu-latest	42s
verify packages / python 3.10 / ubuntu-latest	35s
verify packages / python 3.11 / ubuntu-latest	33s
verify packages / python 3.8 / macos-latest	52s
verify packages / python 3.9 / macos-latest	1m 3s
verify packages / python 3.10 / macos-latest	53s
verify packages / python 3.11 / macos-latest	49s
verify packages / python 3.8 / windows-latest	1m 17s
verify packages / python 3.9 / windows-latest	1m 18s
verify packages / python 3.10 / windows-latest	1m 20s
verify packages / python 3.11 / windows-latest	1m 29s
	18m 7s

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