CI: phytest-timing: detect deviation from normalized values above/below

The CI would only detect a deviation from the normalized value based on
a configurable threshold, typically 1.25 (so we would tolerate a 25%
increase). However, it often happens that a timing gets shorter (e.g.,
forgot to put the timing measurements). This commit introduces a
"Deviation Threshold" (smaller than 1) to not only check that we exceed
1.0 + "Deviation Threshold" (as before), but also that are not below 1.0
- "Deviation Threshold".

In other words, assuming a maximum divergence of 25%, instead of just
checking if val > 1.25, we now also check if val < 0.75 (and flag
error).

ci-scripts/datalog_rt_stats.default.yaml

@@ -5,7 +5,7 @@ Title : Processing Time (us)
 ColNames :
   - Metric
   - Average; Max; Count
-  - Average vs Reference Deviation (Reference Value; Acceptability Threshold)
+  - Average vs Reference Deviation (Reference Value; Acceptability Deviation Threshold)
 Ref : 
   feprx : 43.0
   feptx_prec : 13.0
@@ -20,17 +20,17 @@ Ref :
   DL & UL scheduling timing : 10.0
   UL Indication : 3.0
   Slot Indication : 40.0
-Threshold :
-  feprx : 1.25
-  feptx_prec : 1.25
-  feptx_ofdm : 1.25
-  feptx_total : 1.25
-  L1 Tx processing : 1.25
-  DLSCH encoding : 1.25
-  L1 Rx processing : 1.25
-  PUSCH inner-receiver : 1.25
-  PUSCH decoding : 1.25
-  Schedule Response : 1.25
-  DL & UL scheduling timing : 1.25
-  UL Indication : 1.25
-  Slot Indication : 1.25
+DeviationThreshold :
+  feprx : 0.25
+  feptx_prec : 0.25
+  feptx_ofdm : 0.25
+  feptx_total : 0.25
+  L1 Tx processing : 0.25
+  DLSCH encoding : 0.25
+  L1 Rx processing : 0.25
+  PUSCH inner-receiver : 0.25
+  PUSCH decoding : 0.25
+  Schedule Response : 0.25
+  DL & UL scheduling timing : 0.25
+  UL Indication : 0.25
+  Slot Indication : 0.25