Change default plasma shape initialization from 0 to 1

[chris-ashe]

Description

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.81%. Comparing base (c1e32d4) to head (3e9f5e3).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4150   +/-   ##
=======================================
  Coverage   47.81%   47.81%           
=======================================
  Files         143      143           
  Lines       29993    29993           
=======================================
+ Hits        14341    14342    +1     
+ Misses      15652    15651    -1     

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[je-cook]

Some changes elsewhere need to happen before we can do this