[telegraf] Cannot use `starlark` script as it doesn't accept multipleline string under processors.starlark.source

Gotta issue when trying to implement starlark processor with this instruction [link](https://www.influxdata.com/blog/prometheus-remote-write-support-with-influxdb-2-0/)

###Helm value:
```yaml
config:
processors:
- enum:
mapping:
field: "status"
dest: "status_code"
value_mappings:
healthy: 1
problem: 2
critical: 3
- starlark:
source: |
def apply(metric):
if metric.name == "prometheus_remote_write":
for k, v in metric.fields.items():
metric.name = k
metric.fields["value"] = v
metric.fields.pop(k)
return metric
```
result in `configmap`:
```toml
[[processors.starlark]]
source = "def apply(metric):\n if metric.name == \"prometheus_remote_write\":\n for k, v in metric.fields.items():\n metric.name = k\n metric.fields[\"value\"] = v\n metric.fields.pop(k)\n return metric\n"

```
The issue I was thought it came from the template we had to wrapped by `processor` helm template function
Should we go with this like we did for `telegraf-ds` https://github.com/influxdata/helm-charts/pull/239
I would like to work on this :)

Start by locating the processor Helm template that renders the starlark source, then compare it with the telegraf-ds change in PR #239. Render the chart with the multiline source from this issue and verify that the generated ConfigMap contains valid TOML preserving the script content.

Written by the indexing model from the issue text.