build: Preserve newlines when gathering stdout

[hybrist]

If the chunk happens to end in a new line or other meaningful whitespace, stripping it can lead to two words (e.g. targets) being squished together and broken.

PR Checklist

Please check to confirm your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[hybrist]

See failing CI runs on: https://github.com/angular/angular-cli/actions/runs/13085857756/job/36516887022?pr=29555

[hybrist]

The changes were merged into the following branches: main, 19.1.x

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