[prometheus-thanos] Wrap thanos querier additional flags with quotes

[iemre]

What this PR does / why we need it:

This PR wraps the Thanos Querier additional flags in template with ". This allows us to pass values that have new line characters and/or quotation marks in them. For instance, the tracing.config flag (see here) accepts a YAML string, but currently when the template is rendered with a valid YAML string, the querier does not start because the provided valid YAML gets broken after the template is rendered.

Signed-off-by: Emre Kartoglu iemrek@gmail.com

Special notes for your reviewer:

• I've tested the changes in a private setup.

Checklist

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

• [x] DCO signed
• [x] Chart Version bumped (if the pr is an update to an existing chart)
• [x] Variables are documented in the README.md
• [x] Title of the PR starts with chart name (e.g. [fluentd-elasticsearch])

[iemre]

@axdotl @rpahli could one of you please comment on the change? I'll raise a merge request if it makes sense to you.