Fix `EntityAt` benchmarks to actually use 5 archetypes

[mlange-42]

Query.EntityAt benchmarks did not actually use 5 archetypes, as stated.

[coveralls]

Pull Request Test Coverage Report for Build 7857294193

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 7856208004:	0.0%
Covered Lines:	6226
Relevant Lines:	6226

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💛 - Coveralls