Remove jaegerBackendMigration feature toggle (#107702)

* remove feature toggle if statements

* remove unused impoerts

* remove unused private functions

* prettier

* official ft removal

* fix some failing tests in datasource.test.ts

* clean up test file

* update test names

* remove tests for testDatasource

* remove describe

* tests

* fix import order

* betterer

packages/grafana-data/src/types/featureToggles.gen.ts

@@ -738,11 +738,6 @@ export interface FeatureToggles {
   */
   crashDetection?: boolean;
   /**
-  * Enables querying the Jaeger data source without the proxy
-  * @default true
-  */
-  jaegerBackendMigration?: boolean;
-  /**
   * Enables removing the reducer from the alerting UI when creating a new alert rule and using instant query
   * @default true
   */