Merge remote-tracking branch 'origin/prach-fft' into integration_2025_w52 (!3809)

[FHI72] Fix the PRACH FFT size

ru_config->fftSize is used for the C-plane Section Type 3 which is
dedicated for PRACH and mixed numerology. Previously, we assumed that
PRACH FFT size is equivalent to PxSCH FFT size, but should be based on
the PRACH format.

Tests with the following RUs:

- [x] Benetel v1.2.2 & v1.4.1
- [x] VVDN Gen 3
- [x] Liteon 02.00.10
- [x] Metanoia v2.2.8 (Jura)

executables/nr-ru.c

@@ -896,6 +896,7 @@ static void fill_split7_2_config(split7_config_t *split7, const nfapi_nr_config_
     }
   }
 
+  split7->prach_fftSize = prach_config->prach_sequence_length.value == 0 ? 10 : 8; // need to handle 5kHz cases better than this
   split7->fftSize = log2(fp->ofdm_symbol_size);
 
   // M-plane related parameters