Use consistent default values for locks

What does this MR do and why?

Use consistant default values for locks

Making sure we do not retrieve values when the project returns null, using the same approach as in other Blob and Repository components.

Changelog: other

References

• Fix TypeError regarding pathLocks in blob_content_viewer
• Make sure default values are used when project data is unavailable
• example errors

Screenshots or screen recordings

Before	After
n/a	n/a

How to set up and validate locally

1. Go to Project / Repository and select a file to view
2. Inspect LockDirectoryButton with the Vue devTools
3. Apply the following patch and make sure that devTools show values from BLOB_DEFAULT_INFO

diff --git a/ee/app/assets/javascripts/repository/components/lock_directory_button.vue b/ee/app/assets/javascripts/repository/components/lock_directory_button.vue
index 0f7cc48042e4..0d5b281e6fc6 100644
--- a/ee/app/assets/javascripts/repository/components/lock_directory_button.vue
+++ b/ee/app/assets/javascripts/repository/components/lock_directory_button.vue
@@ -55,13 +55,14 @@ export default {
         };
       },
       update({ project }) {
-        const allPathLocks = project?.pathLocks?.nodes?.map((lock) => this.mapPathLocks(lock));
+        let prj = null;
+        const allPathLocks = prj?.pathLocks?.nodes?.map((lock) => this.mapPathLocks(lock));
         this.pathLock =
           allPathLocks.find(
             (lock) =>
               this.isDownstreamLock(lock) || this.isUpstreamLock(lock) || this.isExactLock(lock),
           ) || {};
-        this.projectUserPermissions = project?.userPermissions || {
+        this.projectUserPermissions = prj?.userPermissions || {
           ...DEFAULT_BLOB_INFO.userPermissions,
           createPathLock: false,
         };

4. With the default value, the Lock button will be seen in a disabled state with a tooltip that you don't have enough permissions to lock.

MR acceptance checklist

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Related to #523410 (closed)