Vault template print the same log again and again

**Describe the bug**

When I use Vault template, a single `spew_printf`, even completely outside of any loop, will be printed randomly multiple times.

This makes the output not readable and very confusing.

**To Reproduce**
Steps to reproduce the behavior:

1. Start a dev vault

```bash
./vault server -dev -dev-root-token-id root
```

2. Write some testing KV

```bash
export VAULT_ADDR="http://127.0.0.1:8200"
export VAULT_TOKEN="root"
for i in {1..10}; do
for s in {1..10}; do
vault kv put -mount=secret override${i}/secret${s} data=$i
done
done
```

3. Setup a template and a Vault configure

```bash
echo root > token

# content of tmpl.hcl
vault {
address = "http://localhost:8200"
}
auto_auth {
method {
type = "token_file"
config = {
token_file_path = "token"
}
}
}
log_level = "info"
exit_after_auth = true
template_config {
exit_on_retry_failure = true
}
template {
source = "test.gotmpl"
destination = "test.out"
}

# content of test.gotmpl
{{ spew_printf "ONLY_PRINT_ONCE\n" }}
{{ $mount := "secret" }}
{{ $cascade_paths := sprig_list
"override1"
"override2"
"override3"
"override4"
"override5"
"override6"
"override7"
"override8"
"override9"
"override10"
-}}
{{ range $cascade_paths -}}
{{ $secret_dir := . -}}
{{ spew_printf "listing %v\n" $secret_dir -}}
{{ range secrets ( printf "%s/metadata/%s" $mount $secret_dir ) -}}
{{ $secret_name := . -}}
{{ $path := ( printf "%s/data/%s/%s" $mount $secret_dir . ) -}}
{{ $metadatapath := ( printf "%s/metadata/%s/%s" $mount $secret_dir . ) -}}
{{ with secret $metadatapath -}}
{{ spew_printf " found secret: %q\n" $path -}}
{{ end -}}
{{ end -}}
{{ end -}}
```

4. Run Vault

```
vault agent -config tmpl.hcl
```

And you get a really messed up output:

`vault agent -config v.hcl | grep -c ONLY_PRINT_ONCE` gives a random number from 0~20 or more.

**Expected behavior**

Expected output should be

```
ONLY_PRINT_ONCE
listing override1
found secret ...
found secret ...
listing override2
found secret ...
found secret ...
```

**Environment:**
* Vault Server Version (retrieve with `vault status`): 1.19.3
* Vault CLI Version (retrieve with `vault version`): 1.19.3
* Server Operating System/Architecture: both macOS and Ubuntu

Vault server configuration file(s):

start with `-dev`

**Additional context**
Add any other context about the problem here.

Start with the Vault Agent command and the template configuration shown in the reproduction, then run the provided dev-server and template steps to observe repeated spew_printf output. Trace why a single print is emitted multiple times, and verify that the command produces each expected line once, including ONLY_PRINT_ONCE.

Written by the indexing model from the issue text.