Fix declarative config env substitution by disallowing '}' in default value

[jack-berg]

No description provided.

[jack-berg]

Without this fix, this resolves to value1 default} ${STR_2.

The regex isn't able to differentiate between the } ending the second env var reference and the } ending the third reference.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.10%. Comparing base (b1cd30e) to head (b137719).
Report is 6 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6793      +/-   ##
============================================
- Coverage     90.12%   90.10%   -0.02%     
+ Complexity     6546     6545       -1     
============================================
  Files           728      728              
  Lines         19702    19702              
  Branches       1935     1935              
============================================
- Hits          17756    17753       -3     
  Misses         1347     1347              
- Partials        599      602       +3     

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