Use GitlabUploader#filename when generating upload URLs

What does this MR do?

Use GitlabUploader#filename when generating upload URLs.

When ObjectStorage is used, this method returns the file name passed to us from workhorse rather than getting it from file.filename.

There are encoding issues when we use file.filename with a remote CarrierWave::Storage::Fog::File. This happens when direct uploads are enabled. See https://gitlab.com/gitlab-org/gitlab-ce/issues/53357#note_184110472

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

#53357 (closed)