Fix volume attachment with dstack backend #3756

Job	Run time
python-lint	19s
docs-build	59s
frontend-build	1m 6s
gateway-build	13s
runner-test	44s
runner-compile (linux, amd64, ubuntu-latest)	26s
python-test (macos-latest, 3.9)	3m 7s
python-test (macos-latest, 3.10)	2m 24s
python-test (macos-latest, 3.11)	2m 11s
python-test (macos-latest, 3.12)	2m 13s
python-test (macos-latest, 3.13)	2m 10s
python-test (ubuntu-latest, 3.9)	5m 6s
python-test (ubuntu-latest, 3.10)	5m 10s
python-test (ubuntu-latest, 3.11)	4m 32s
python-test (ubuntu-latest, 3.12)	4m 49s
python-test (ubuntu-latest, 3.13)	4m 53s
python-test (windows-latest, 3.9)	6m 17s
python-test (windows-latest, 3.10)	4m 22s
python-test (windows-latest, 3.11)	4m 27s
python-test (windows-latest, 3.12)	3m 56s
python-test (windows-latest, 3.13)	6m 6s
runner-upload	20s
update-get-dstack	11s
generate-json-schema	25s
	1h 6m 26s

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