refactor(ObjectStoreStorage): light refactoring of writeStream

[joshtrichards]

• Resolves: #

Summary

We may want to split this function up into a few focused private methods, but this refactor is just focused on:

• adding some helpful inline comments to make it easier to follow the logic/flow
• streamlining logging logic
• Making sure metadata works with when size is `0

TODO

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI