`measure_pauli_strings` not combining readout measurement circuits

[eliottrosenberg]

#7236 added the ability to specify groups of qubit-wise-commuting Pauli operators to measure simultaneously. Because these measurements are done simultaneously, readout on the qubits that these operators act on should also be measured simultaneously, but instead the code is generating a different readout circuit for each Pauli.

[eliottrosenberg]

@ddddddanni

[mhucka]

Discussed during Cirq Cynq 2025-06-11: @eliottrosenberg would you be able to provide a little bit more information?

[ddddddanni]

I'm having #7416 to fix this.

[eliottrosenberg]

@mhucka happy to provide more context if you want, but it seems that @ddddddanni has it covered!