docs: fix otlp guide - collector config example

[arukiidou]

What this PR does / why we need it:

• relates Support receiving logs in Loki using OpenTelemetry OTLP #5346

The current documentation seems to work, but the naming may cause confusion.
And not match Collector docs usage.

For example, consider the case where using loki and mimir

service:
  pipelines:
    # its mimir
    metrics_:
      receivers: [otlp]
      processors: [batch]
      exporters: [otlphttp/mimir]
    # its loki❓
    metrics:
      receivers: [otlp]
      processors: [batch]
      exporters: [otlphttp/loki]

Perhaps following is the common naming:

service:
  pipelines:
    # its mimir✅
    metrics:
      receivers: [otlp]
      processors: [batch]
      exporters: [otlphttp/mimir]
    # its loki✅
    logs:
      receivers: [otlp]
      processors: [batch]
      exporters: [otlphttp/loki]

Which issue(s) this PR fixes:

• none.

Special notes for your reviewer:

• none.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• CHANGELOG.md updated
  • If the change is worth mentioning in the release notes, add add-to-release-notes label
• 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

[CLAassistant]

All committers have signed the CLA.

[sandeepsukhani]

Thanks for fixing it! LGTM

[grafanabot]

The backport to release-2.9.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-12328-to-release-2.9.x origin/release-2.9.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 03982c218ec3e6549068b5ed1ebecd3514126123

When the conflicts are resolved, stage and commit the changes:

git add . && git cherry-pick --continue

If you have the GitHub CLI installed:

# Push the branch to GitHub:
git push --set-upstream origin backport-12328-to-release-2.9.x
# Create the PR body template
PR_BODY=$(gh pr view 12328 --json body --template 'Backport 03982c218ec3e6549068b5ed1ebecd3514126123 from #12328{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title "chore: [release-2.9.x] docs: fix otlp guide - collector config example" --body-file - --label "size/XS" --label "type/docs" --label "backport" --base release-2.9.x --milestone release-2.9.x --web

Or, if you don't have the GitHub CLI installed (we recommend you install it!):

# Push the branch to GitHub:
git push --set-upstream origin backport-12328-to-release-2.9.x

# Create a pull request where the `base` branch is `release-2.9.x` and the `compare`/`head` branch is `backport-12328-to-release-2.9.x`.

# Remove the local backport branch
git switch main
git branch -D backport-12328-to-release-2.9.x