fix(@schematics/angular): remove EnvironmentInjector import in functional guard spec

[cexbrayat]

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?

It is unnecessary now that the spec uses runInInjectionContext
The resolver spec does not have this issue as the import was missing in the spec in the first place.

Does this PR introduce a breaking change?

• Yes
• No

Other information

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