[Filesystem] fix lock file permissions
bug #12770 [Filesystem] fix lock file permissions (nicolas-grekas)

This PR was merged into the 2.6 branch.

Discussion
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[Filesystem] fix lock file permissions

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12589, #12634
| License       | MIT
| Doc PR        | -

This PR replaces #12634. It tunes permissions on lock files so that locking is allowed for any OS user.

Commits
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ceecb50 [Filesystem] fix lock file permissions