Add targeted indexes to improve query performance (#1783)

Signed-off-by: Denislav Prinov <denislav.prinov@bosch.com>

hawkbit-repository/hawkbit-repository-jpa/src/main/resources/db/migration/POSTGRESQL/V1_12_30__add_indexes___POSTGRESQL.sql

@@ -0,0 +1,11 @@
+CREATE INDEX sp_idx_rollouttargetgroup_target_id
+    ON sp_rollouttargetgroup
+    USING BTREE (target_id);
+
+CREATE INDEX sp_idx_target_attributes_target_id
+    ON sp_target_attributes
+    USING BTREE (target_id);
+
+CREATE INDEX sp_idx_action_target
+    ON sp_action
+    USING BTREE (target);