Fix class40 example units

[greschd]

The class40 CDB file is in MKS units, not MPA. Update the advanced PyMAPDL workflow example to use the correct units.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.97%. Comparing base (f127459) to head (d7d2673).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #914   +/-   ##
=======================================
  Coverage   94.97%   94.97%           
=======================================
  Files         110      110           
  Lines        5773     5773           
  Branches      296      296           
=======================================
  Hits         5483     5483           
  Misses        289      289           
  Partials        1        1           

Flag	Coverage Δ
direct-launch	92.20% <ø> (ø)
minimum-deps	93.07% <ø> (ø)
python-3.10	94.16% <ø> (ø)
python-3.11	94.09% <ø> (ø)
python-3.12	94.09% <ø> (ø)
python-3.13	94.33% <ø> (ø)
server-2024R2SP5	90.49% <ø> (ø)
server-2025R1SP4	94.12% <ø> (ø)
server-2025R2SP2	94.09% <ø> (ø)
server-2026R1	94.09% <ø> (ø)
server-latest	94.73% <ø> (ø)

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