[configoptional] Fix behavior when unmarshaling with 'enabled: false'

[mx-psi]

Description

Updates configoptional.Optional.Unmarshal to set the inner value to the zero value when the resulting value is a configoptional.None.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.13%. Comparing base (9e38bee) to head (a9131d0).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14218      +/-   ##
==========================================
- Coverage   92.14%   92.13%   -0.01%     
==========================================
  Files         666      666              
  Lines       41441    41443       +2     
==========================================
- Hits        38186    38185       -1     
- Misses       2216     2218       +2     
- Partials     1039     1040       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jmacd]

As discussed in #14155 and the corresponding contrib PR, there are a few tests where this will help. The specific circumstances we identified were:

• component sets QueueBatchConfig to enabled by default using configoptional.Some()
• component tests that enabled: false disables the feature
• component tests equality with an expected Optional[T]

Without this fix, we can't construct the correct Optional[T] expectation, because the Unmarshal yields flavor=none with a non-zero value. With this fix, we will test with configoptional.NoneT after enabled: false.

[codspeed-hq]

CodSpeed Performance Report

Merging #14218 will not alter performance

_{Comparing mx-psi:mx-psi/scrub-zero-value-contents (a9131d0) with main (9e38bee)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 118 untouched