Fix external fts example

[urfeex]

This example seems to fail on CB3 a lot recently. This PR attempts to fix that.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.69%. Comparing base (f96fe15) to head (526d6c3).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #504      +/-   ##
==========================================
- Coverage   76.88%   76.69%   -0.20%     
==========================================
  Files         113      116       +3     
  Lines        6056     6341     +285     
  Branches     2644     2761     +117     
==========================================
+ Hits         4656     4863     +207     
- Misses       1063     1127      +64     
- Partials      337      351      +14     

Flag	Coverage Δ
python_scripts	75.90% <ø> (ø)
start_ursim	83.88% <ø> (-0.68%)	⬇️
ur20-latest	72.93% <ø> (+0.59%)	⬆️
ur5-3.14.3	?
ur5e-10.11.0	66.98% <ø> (+0.90%)	⬆️
ur5e-10.12.0	68.22% <ø> (+0.86%)	⬆️
ur5e-10.7.0	66.44% <ø> (+0.86%)	⬆️
ur5e-5.9.4	73.51% <ø> (+0.67%)	⬆️

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