fix(helm): Removed duplicate bucketNames from documentation and fixed key name deploymentMode

[ddaskal]

What this PR does / why we need it:
Fixes documentation for Helm deployments to not have duplicate values and utilize correct deploymentMode key name.

Which issue(s) this PR fixes:
Fixes #12610

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
• 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.

[JStickler]

@ddaskal Please note this item in the PR checklist and update the other files, and sign the contributor license agreement.
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

[ddaskal]

@JStickler I believe this is ready for review again. Do I need to squash my commits first or are you able to do a squash & merge?

[JStickler]

@ddaskal No need to squash, we squash and merge. I've already tagged someone who works on the Helm charts to review this (I'm the technical writer on the team, so I only approve doc updates and leave the code changes to the engineering team).

[MichelHollands]

LGTM

[grafanabot]

The backport to release-3.0.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-12641-to-release-3.0.x origin/release-3.0.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 0d8ff9ee7929b8facbdb469abe344c320d3bd5ce

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-12641-to-release-3.0.x
# Create the PR body template
PR_BODY=$(gh pr view 12641 --json body --template 'Backport 0d8ff9ee7929b8facbdb469abe344c320d3bd5ce from #12641{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title 'chore: [release-3.0.x] fix(helm): Removed duplicate bucketNames from documentation and fixed key name `deploymentMode`' --body-file - --label 'size/S' --label 'area/helm' --label 'type/docs' --label 'backport' --base release-3.0.x --milestone release-3.0.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-12641-to-release-3.0.x

# Create a pull request where the `base` branch is `release-3.0.x` and the `compare`/`head` branch is `backport-12641-to-release-3.0.x`.

# Remove the local backport branch
git switch main
git branch -D backport-12641-to-release-3.0.x