chore: increase stack sampling for python

[GuillaumeLagrange]

mitigates unwinding issues that now impact the flamegraph's topology much more than before since we do not merge simply by symbol name

[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks

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_{Comparing bigger-dwarf-sampling-python (ffe493a) with main (31cbb9d)}

[not-matthias]

make sure to test the changes on pytest-codspeed (we previously had issues with large perf.data files)