Plugins: Ensure plugin uninstall success for "pre-installed" community plugins (#55322)

* track pre-installed external plugins in store

* fix tests

pkg/plugins/storage/fs.go

@@ -61,10 +61,6 @@ func (fs *FS) Add(ctx context.Context, pluginID string, pluginArchive *zip.ReadC
 		})
 	}
 
-	fs.mu.Lock()
-	fs.store[pluginID] = pluginDir
-	fs.mu.Unlock()
-
 	return &ExtractedPluginArchive{
 		ID:           res.ID,
 		Version:      res.Info.Version,
@@ -73,6 +69,14 @@ func (fs *FS) Add(ctx context.Context, pluginID string, pluginArchive *zip.ReadC
 	}, nil
 }
 
+func (fs *FS) Register(_ context.Context, pluginID, pluginDir string) error {
+	fs.mu.Lock()
+	fs.store[pluginID] = pluginDir
+	fs.mu.Unlock()
+
+	return nil
+}
+
 func (fs *FS) Remove(_ context.Context, pluginID string) error {
 	fs.mu.RLock()
 	pluginDir, exists := fs.store[pluginID]

pkg/plugins/storage/ifaces.go

@@ -7,5 +7,6 @@ import (
 
 type Manager interface {
 	Add(ctx context.Context, pluginID string, rc *zip.ReadCloser) (*ExtractedPluginArchive, error)
+	Register(ctx context.Context, pluginID, pluginDir string) error
 	Remove(ctx context.Context, pluginID string) error
 }