[BUG][Opensearch] Redundant line in networkpolicy template

[smlx]

Describe the bug
The networkpolicy template contains a redundant line.

To Reproduce
Steps to reproduce the behavior:

1. Click here
2. See redundant line.

Expected behavior
creationTimestamp should not be in templates since it only makes sense for an instantiated object.

Chart Name
Opensearch

Screenshots
n/a

Host/Environment (please complete the following information):

• Helm Version: v3.6.2
• Kubernetes Version: 1.20.7

Additional context
n/a