Simplify units code in subarray

[maxnoe]

No description provided.

[codecov]

Codecov Report

Merging #1950 (280e152) into master (cbb01b5) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1950   +/-   ##
=======================================
  Coverage   92.07%   92.07%           
=======================================
  Files         191      191           
  Lines       15088    15088           
=======================================
  Hits        13893    13893           
  Misses       1195     1195           

Impacted Files	Coverage Δ
ctapipe/instrument/subarray.py	93.33% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cbb01b5...280e152. Read the comment docs.

[LukasNickel]

Why can we not use pos.to(u.m) directly without the value dance?

[maxnoe]

A list of quantities is not the same as an array quantity.

[LukasNickel]

Right, thx