[sram_ctrl/dv] Adapt throughput tests for readback mode

[nasahlpa]

Description

With the introduction of the readback mode (c.f., #23212), the throughput tests need to be adapted to take the additional delay introduced by this feature into account. Currently, the readback feature is disabled for these tests.

[vogelpi]

This seems doable without huge effort but the priority isn't very high as the feature can be disabled at run time.

[vogelpi]

This doesn't seem like a priority to me. I suggest moving to M7.