[Bug] Token is not updated if a function is updated

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Read release policy

- [X] I understand that unsupported versions don't get bug fixes. I will attempt to reproduce the issue on a supported version of Pulsar client and Pulsar broker.

### Version

Pulsar 3.2.3 in a kubernetes env (v1.29.6)

### Minimal reproduce step

Create a GO function using a TOKEN_A

`/bin/pulsar-admin \
--admin-url $ADMIN_URL \
--auth-params TOKEN_A\
--auth-plugin org.apache.pulsar.client.impl.auth.AuthenticationToken \
functions create \
--function-config-file $CONFIG_FILE \
--go $BIN_PATH \
--name $FUNCTION_NAME \
--parallelism $PARALLELISM \
--cpu $CPU \
--ram $RAM \
--user-config "$USER_CONFIG_JSON"`

The function is created and the TOKEN_A is placed under /etc/auth/token

Update the function using TOKEN_B

`/bin/pulsar-admin \
--admin-url $ADMIN_URL \
--auth-params TOKEN_B\
--auth-plugin org.apache.pulsar.client.impl.auth.AuthenticationToken \
functions update \
--function-config-file $CONFIG_FILE \
--go $BIN_PATH \
--name $FUNCTION_NAME \
--parallelism $PARALLELISM \
--cpu $CPU \
--ram $RAM \
--user-config "$USER_CONFIG_JSON"`

### What did you expect to see?

The function is updated and the TOKEN_B is placed under /etc/auth/token

### What did you see instead?

The function is updated and the TOKEN_A is placed under /etc/auth/token

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Reproduce the issue with the Pulsar 3.2.3 pulsar-admin functions create and functions update commands in the reported Kubernetes environment, changing TOKEN_A to TOKEN_B. Inspect how the update command handles authentication credentials and how the function runtime populates /etc/auth/token; done means the updated function uses TOKEN_B rather than TOKEN_A.

Written by the indexing model from the issue text.