[synthetics] Fix indent for env in private location chart

[ruizb]

What this PR does / why we need it:

Following the changes in:

• https://github.com/DataDog/helm-charts/pull/1354

The indentation for env got broken in the deployment template. This PR fixes it.

After uncommenting the env example in values.yaml, helm template .:

Before

Error: YAML parse error on synthetics-private-location/templates/deployment.yaml: error converting YAML to JSON: yaml: line 41: did not find expected key

Use --debug flag to render out invalid YAML

After

---
# Source: synthetics-private-location/templates/service_account.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: release-name-synthetics-private-location
  labels:
    helm.sh/chart: synthetics-private-location-0.15.31
    app.kubernetes.io/name: synthetics-private-location
    app.kubernetes.io/instance: release-name
    app.kubernetes.io/version: "1.46.0"
    app.kubernetes.io/managed-by: Helm
---
# Source: synthetics-private-location/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: release-name-synthetics-private-location
...
...
...
          resources:
            {}
          env:
            - name: <ENV_VAR_NAME>
              value: <ENV_VAR_VALUE>
      volumes:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [x] Chart Version bumped
• [x] Documentation has been updated with helm-docs (run: .github/helm-docs.sh)
• [x] CHANGELOG.md has been updated
• [ ] ~Variables are documented in the README.md~
• [ ] ~For Datadog Operator chart or value changes update the test baselines (run: make update-test-baselines)~

[ruizb]

@loutPhilipps I updated the description accordingly 👍