This commit updates the cloneRequestAndPatchHeaders function to patch the Headers.forEach method. This ensures that host headers are validated when the application iterates over request headers using forEach, preventing potential host header injection attacks during header iteration.

A unit test has been added to validation_spec.ts to verify that forEach correctly triggers validation and throws an error for disallowed hosts.

(cherry picked from commit bcd99f9)

See associated pull request for more information.

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The VALID_HOST_REGEX has been updated to include the underscore
character. This ensures that hostnames containing underscores (e.g., in
some internal or development environments) are correctly validated
instead of being rejected.

Closes #32835

(cherry picked from commit e7e434c)

(cherry picked from commit 87d99e9)

See associated pull request for more information.