Telegraf helm chart output tagpass and tagdrop should not generate double brackets

Same issue like in #375 just this time for outputs.

values.yaml:

```
outputs:
- basicstats:
period: "30s"
drop_original: true
stats:
- "sum"
taginclude:
- "counter"
- "sql_instance"
tagpass:
counter:
- "Blocked tasks"
- "CPU usage %"
- "Used memory (KB)"
```

expected output:

```
[[outputs.basicstats]]
drop_original = true
period = "30s"
stats = [
"sum"
]
taginclude = [
"counter",
"sql_instance"
]
[outputs.basicstats.tagpass]
counter = [
"Blocked tasks",
"CPU usage %",
"Used memory (KB)"
]
```

actual output:

```
[[outputs.basicstats]]
drop_original = true
period = "30s"
stats = [
"sum"
]
taginclude = [
"counter",
"sql_instance"
]
[[outputs.basicstats.tagpass]]
counter = [
"Blocked tasks",
"CPU usage %",
"Used memory (KB)"
]
```

Start with the Helm chart templates that render output tagpass and tagdrop, using the values.yaml example and issue #375 as references. Confirm the generated TOML uses a single-bracket [outputs.basicstats.tagpass] table rather than double brackets, while preserving the shown output fields.

Written by the indexing model from the issue text.