fix: handle NoValidConnectionsError properly in SSHCE #14382

Job	Run time
pre-commit	1m 11s
DiracX Unit Tests	2m 24s
Pylint for Python 2.7 in Pilot files	51s
check-py314 (pytest --runslow -k 'not test_BaseType_Unicode and not test_nestedStructure')	14m 17s
shellcheck	5s
check (mypy)	2m 30s
check-py314 (pylint -j 0 -E src/)	3m 28s
check (pylint -j 0 -E src/)	3m 30s
pycodestyle	6s
check (pytest --runslow -k 'not test_BaseType_Unicode and not test_nestedStructure')	13m 59s
	42m 21s

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