fix(helm): fix extraObjects

[hervenicol]

What this PR does / why we need it:

Fixes a regression introduced with #12397

When we had multiple extraObjects the rendering was missing linefeed before the separation triple-dashes (---).
Like here:

apiVersion: testResource/v1alpha1
kind: testResource
metadata:
  name: test1
spec: void---
apiVersion: testResource/v1alpha1
kind: testResource
metadata:
  name: test2
spec: void---
apiVersion: testResource/v1alpha1
kind: testResource
metadata:
  name: test3
spec: void
---

With the fix it looks like this:

apiVersion: testResource/v1alpha1
kind: testResource
metadata:
  name: test1
spec: void
---
# Source: loki/templates/extra-manifests.yaml
apiVersion: testResource/v1alpha1
kind: testResource
metadata:
  name: test2
spec: void
---
# Source: loki/templates/extra-manifests.yaml
apiVersion: testResource/v1alpha1
kind: testResource
metadata:
  name: test3
spec: void
---

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[QuentinBisson]

@MichelHollands could you please take a look at this patch?

[hervenicol]

Maybe @TheRealNoob would be interested in having a look at it as well.

[QuentinBisson]

@MichelHollands @jeschkies is there a way to help merging this PR? The change is really small and it fixes a real issue

[QuentinBisson]

Thank you :)

[TheRealNoob]

@hervenicol sorry I missed this notification. Apologies for not catching this! Thank you for fixing it

[QuentinBisson]

@TheRealNoob I think we forgot to bump the chart version in this PR