[contributing.md] swap cypress command order

[williaster]

@michellethomas running the commands in the previous order failed for me, but worked after first running db upgrade (this seems to mirror other parts of the contributing.md + cypress_build.sh files as well)

[michellethomas]

oh thanks, I was just about to do this 👍

[codecov-io]

Codecov Report

Merging #5921 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #5921      +/-   ##
=========================================
+ Coverage   63.66%   63.7%   +0.04%     
=========================================
  Files         386     386              
  Lines       23538   23538              
  Branches     2628    2628              
=========================================
+ Hits        14986   14996      +10     
+ Misses       8539    8529      -10     
  Partials       13      13

Impacted Files	Coverage Δ
superset/connectors/sqla/models.py	81.13% <0%> (+0.75%)	⬆️
superset/db_engine_specs.py	55.45% <0%> (+0.87%)	⬆️

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