Add retry logic for vSphere template validation

Sometimes vSphere template validations fail prematurely when checking that the template exists & that it has the required tags. Placing this validation in a retry could help avoid these premature failures

The issue concerns vSphere template validation for template existence and required tags, but it names no file, test, or entry point. Start by locating that validation and existing retry patterns, then verify that transient validation failures are retried and that a template only fails after the retry behavior is exhausted.

Written by the indexing model from the issue text.