read methods use `task.in_stream.channels_to_read`, which is slow

[bkeryan]

Bug Report

Profiling shows that the read methods are spending most of their time querying task.in_stream.channels_to_read.

https://github.com/ni/nidaqmx-python/pull/842/files#r2380592910

Repro or Code Sample

Run benchmarks from #842

Expected Behavior

Most of the time is spent in generated\nidaqmx_library_interpreter.py:4205(read_analog_f64)

Current Behavior

Most of the time is spent in nidaqmx\task_in_stream.py:158(channels_to_read)

Possible Solution

Use task.in_stream.num_chans

Context

Reviewing #842

Your Environment

• Operating system and version: Windows 10
• NI-DAQmx version: 2025 Q3
• nidaqmx-python version: Add benchmarks for stream readers and stream writers #842
• Python version: 3.11.9

AB#3330619