fix: include max_length in continue expconf

[azhou-determined]

Ticket

Description

Test Plan

Continue an old experiment (pre 0.38.0 release) and make sure it continues successfully.

Checklist

• Changes have been manually QA'd
• New features have been approved by the corresponding PM
• User-facing API changes have the "User-facing API Change" label
• Release notes have been added as a separate file under docs/release-notes/
  See Release Note for details.
• Licenses have been included for new code which was copied and/or modified from any external code

[netlify]

✅ Deploy Preview for determined-ui ready!

Name	Link
🔨 Latest commit	75336d6
🔍 Latest deploy log	https://app.netlify.com/sites/determined-ui/deploys/67252a4ed8a4110008a28463
😎 Deploy Preview	https://deploy-preview-10188--determined-ui.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 54.04%. Comparing base (21b0256) to head (75336d6).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
webui/react/src/utils/experiment.ts	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10188      +/-   ##
==========================================
- Coverage   58.46%   54.04%   -4.42%     
==========================================
  Files         754      448     -306     
  Lines      104301    77324   -26977     
  Branches     3642     3644       +2     
==========================================
- Hits        60982    41793   -19189     
+ Misses      43186    35398    -7788     
  Partials      133      133              

Flag	Coverage Δ
harness	?
web	54.30% <85.71%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
webui/react/src/types.ts	99.70% <100.00%> (+<0.01%)	⬆️
webui/react/src/utils/experiment.ts	90.61% <66.66%> (-0.18%)	⬇️

... and 306 files with indirect coverage changes