Add centroid benchmarks for geoshape

[craigtaverner]

We already have centroid benchmarks for both QueryDSL and ES|QL over geo_point in the geopoint track. This PR adds similar benchmarks for the geoshape track, since Elasticsearch ES|QL recently got support for geo_shape in ST_CENTROID_AGG.

Centroid / bounds benchmark results (geoshape)

Tasks containing centroid or bounds. Latency = 50th percentile (ms). Empty cell = no result for that variant.

centroid	bounds	filter	QueryDSL (ms)	ESQL (ms)
	X		831.06	507.18
X	X		2516.20	731.06
X			1242.26	457.93
	X	X	145.26	106.82
X	X	X	385.14	142.79
X		X	173.66	97.45

(filter = polygon in task name)

[esbenchmachine]

@craigtaverner
A backport is pending for this PR.
Apply all the labels that correspond to Elasticsearch minor versions expected to work with this PR, but select only from the available ones.
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In case of merge conflicts during backporting, create the backport PR manually following the steps from README:
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1. Ensure the correct version labels exist in this PR.
2. Ensure each backport pull request is labeled with backport.
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4. Remove backport pending label from this PR once all backport PRs are merged.

Thank you!