Normalize `IndexSet.data` DB storage #469

Job	Run time
Code quality	50s
py3.10 \| backend=sqlite,rest-sqlite,postgres,rest-postgres \| with-pyarrow=false \| pgsql=16 \| pandas=false	15m 6s
py3.11 \| backend=sqlite,rest-sqlite,postgres,rest-postgres \| with-pyarrow=false \| pgsql=16 \| pandas=false	14m 22s
py3.12 \| backend=sqlite,rest-sqlite,postgres,rest-postgres \| with-pyarrow=false \| pgsql=16 \| pandas=false	14m 57s
py3.12 \| backend=sqlite,rest-sqlite \| with-pyarrow=true \| pgsql=16 \| pandas=false	4m 48s
py3.12 \| backend=postgres,rest-postgres \| with-pyarrow=false \| pgsql=15 \| pandas=false	9m 6s
py3.11 \| backend=sqlite,rest-sqlite \| with-pyarrow=true \| pgsql=16 \| pandas=2.1.3	4m 13s
py3.10 \| backend=sqlite,rest-sqlite \| with-pyarrow=true \| pgsql=16 \| pandas=2.1.0	4m 9s
	1h 7m 31s

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