chore: Configure Renovate (#3755)

* Add renovate.json

* Attempt to make testing/compile-only dependencies opt-in via dependency dashboard

* Update renovate.json

Co-authored-by: Victor Martinez <[email protected]>

* Update renovate.json

---------

Co-authored-by: elastic-renovate-prod[bot] <174716857+elastic-renovate-prod[bot]@users.noreply.github.com>
Co-authored-by: Jonas Kunz <[email protected]>
Co-authored-by: Victor Martinez <[email protected]>

Author: 3 people

renovate.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "github>elastic/renovate-config:only-chainguard"
+  ]
+}