Update AstraDBGraphVectorStore to match implementation of CassandraGraphVectorStore #318

Job	Run time
build	4s
cd libs/astradb / make integration_tests #3.12	14m 21s
cd libs/astradb / make test #3.9	39s
cd libs/astradb / make lint #3.9	59s
cd libs/astradb / make test #3.10	1m 55s
cd libs/astradb / poetry run pytest -m compile tests/integration_tests #3.9	17s
cd libs/astradb / make lint #3.12	2m 4s
cd libs/astradb / poetry run pytest -m compile tests/integration_tests #3.10	2m 1s
cd libs/astradb / make test #3.11	29s
cd libs/astradb / poetry run pytest -m compile tests/integration_tests #3.11	29s
cd libs/astradb / make test #3.12	28s
cd libs/astradb / poetry run pytest -m compile tests/integration_tests #3.12	27s
CI Success	1s
	24m 14s

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