packages: remove gcplock during packages upload

What

this lock was added while debugging a problem related to scheduled pipelines. It worked for a about 3 months and this week it started misbehaving.

I feel it's ok to remove this lock as it was an attempt to fix a bug, but it actually didn't fix it (it was fixed afterwards here : !16481 (merged) ).

I'm not even sure this lock is strictly needed. Surely didn't hurt, but if it's now a problem, I'm happy to remove it.

Why

How

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR