Update params for Python Combine Flink load tests

[jrmccluskey]

The container environment flag for the batch combine flink load tests was not updated to 3.9, causing a mismatch.

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[jrmccluskey]

R: @Abacn

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[Abacn]

ah I did same fix here - #32630

[jrmccluskey]

Ah that works for me, we can use that PR