Dashboard Migrations: V6 pulldowns to annotations; variables (#112221)

* migrate to v19

* migrate to v18

* Migration to be verified: v17 Convert minSpan to maxPerRow in panels

* Migration to be verified: 16 Grid layout migration

* Refactor v17 and v19 migrations to use shared helper functions

* Migration to be verified: 15 No-op migration for schema consistency

* Migration to be verified: 14 Shared crosshair to graph tooltip migration

* cleanup

* wip

* complete migration

* fix lint issues

* refactor and test with minimal graph config

* update tests

* migrate to v12

* extract defaults outside the func

* lint

* lint

* add missing showValues prop

* migrate to v11

* migrate to v10

* add test files

* update

* migrate to v9

* migrate to v8

* add context and fix latest version

* add context

* add context

* generate snapshots

* v13 should be no-op

* clean up

* fix tests

* add context

* snapshots

* generate snapshots

* update

* snapshots

* wip

* fix test

* remove nav when cleaning up defaults

* migrate to v6

* update comments

* remove v28

* remove singlestat migraiton from frontend migrator because this is an automigration

* remove unused function

* Remove v24 table plugin logic

* cleanup

* remove plugin version for automigrate as it was used only in v24 and v28 that have been removed

* cleanup

* update snapshot

* update snapshot

* update snapshot

* update snapshot

* remove test

---------

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

apps/dashboard/pkg/migration/frontend_defaults.go

@@ -66,7 +66,6 @@ func applyFrontendDefaults(dashboard map[string]interface{}) {
 	sortPanelsByGridPos(dashboard)
 
 	// Built-in components
-	addBuiltInAnnotationQuery(dashboard)
 	initMeta(dashboard)
 
 	// Variable cleanup
@@ -1053,7 +1052,8 @@ func cleanupDashboardDefaults(dashboard map[string]interface{}) {
 	// These properties are lost during frontend's property copying loop in getSaveModelCloneOld()
 	delete(dashboard, "preload")   // Transient dashboard loading state
 	delete(dashboard, "iteration") // Template variable iteration timestamp
-	delete(dashboard, "nav")
+	delete(dashboard, "nav")       // Removed after V7 migration
+	delete(dashboard, "pulldowns") // Removed after V6 migration - frontend doesn't have this property
 }
 
 // cleanupFieldConfigDefaults removes properties that frontend considers as defaults and omits