Fix handling of short gzip metadata files

What does this MR do and why?

This backports !177221 (merged) to 17-7-stable-ee.

Previously if a gzip file were less than 10 bytes, HttpIO#read(10) would return a blank string instead of nil. This could cause Zlib::GzipReader to spin indefinitely, waiting for data that is not present.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/372134

MR acceptance checklist

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• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The MR that fixed the bug on the default branch has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
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• Ensure the e2e:test-on-omnibus-ee job has either succeeded or been approved by a Software Engineer in Test.

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