Issue #1919214 by vijaycs85, Abhishek_R_Shah: Create configuration schemas for tracker module.

core/modules/tracker/config/schema/tracker.schema.yml

+# Schema for the configuration files of the tracker module.
+
+tracker.settings:
+  type: mapping
+  label: 'Tracker settings'
+  mapping:
+    cron_index_limit:
+      type: integer
+      label: 'Cron index limit'