vacuum: return none on is_water_box_attached if unsupported

[rytilahti]

Fixes #1168

[codecov-commenter]

Codecov Report

Merging #1178 (e2542e2) into master (506247e) will decrease coverage by 0.01%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master    #1178      +/-   ##
==========================================
- Coverage   78.30%   78.28%   -0.02%     
==========================================
  Files          84       84              
  Lines        9518     9520       +2     
  Branches      775      776       +1     
==========================================
  Hits         7453     7453              
- Misses       1879     1880       +1     
- Partials      186      187       +1     

Impacted Files	Coverage Δ
...o/integrations/vacuum/roborock/vacuumcontainers.py	76.70% <50.00%> (-0.63%)	⬇️

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