Only use custom cli-hydrogen package in development

[amcaplan]

Summary

Fixes shop/issues-develop#21438 - CLI crash caused by malformed JSON in package.json during Hydrogen monorepo detection.

Problem

The CLI was crashing with error "Expected double-quoted property name in JSON" when the project's root package.json contained malformed JSON (trailing commas, missing quotes, etc.)

Error Impact:

• 5 events, 2 affected users, 1 shop in last 7 days
• Complete CLI failure - no commands could run

Cause

• We check for a custom cli-hydrogen package and prefer it to the included package
• This is only really useful in dev environments
• The code only validated file existence, not JSON validity

Solution

• Only do this workaround in development environments

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	79.24% (+0.01% 🔼)	13566/17121
🟡	Branches	73.07% (+0.03% 🔼)	6621/9061
🟡	Functions	79.36%	3498/4408
🟡	Lines	79.59% (+0.01% 🔼)	12812/16097

Test suite run success

3351 tests passing in 1372 suites.

Report generated by 🧪jest coverage report action from c30af25