Fix issparse for AbstractVectorOfArray #1013

Job	Run time
SciMLBase.jl/Core/1	6m 35s
DiffEqBase.jl/Downstream/1	21m 18s
DiffEqBase.jl/Downstream2/1	18m 5s
SciMLSensitivity.jl/Core2/1	20m 26s
DiffEqSensitivity.jl/Core/1	21m 40s
SciMLSensitivity.jl/Core6/1	20m 31s
OrdinaryDiffEq.jl/Interface/1	1h 18m 35s
DiffEqBase.jl/Core/1	4m 8s
SciMLSensitivity.jl/Core4/1	21m 2s
OrdinaryDiffEq.jl/Core/1	13m 14s
DelayDiffEq.jl/Interface/1	17m 25s
SciMLSensitivity.jl/Core3/1	20m 34s
SciMLSensitivity.jl/Core5/1	31s
SciMLSensitivity.jl/Core1/1	19m 36s
LabelledArrays.jl/RecursiveArrayTools/1	6m 41s
	4h 50m 21s

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