[Object storage] Set direct_upload=true and background_upload=false

What does this MR do?

In gitlab-com/gl-infra&734 (closed), we are attempting to remove background upload. The deprecation message was sent out for a while. To ensure that the deprecation was safe and gradual, we break the whole process into multiple iterations:

• Set direct_upload=true and background_upload=false in omnibus
• Remove those configurations completely
• Remove the code paths related to background_upload

This MR is to set the default configuration of background_upload to false and direct_upload to true. This MR touches the configurations of each component only. If the consolidated object storage configuration is set, background_upload is disabled by default. Also, some components, such as pages, ci_secure_files, and terraform_states don't support neither direct_upload nor background_upload.

Related issues

Closes gitlab-com/gl-infra/scalability#1688 (closed)

Checklist

See Definition of done.

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Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
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Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
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