Issue-275: Honor existingAgentk8sglueSecret in deployment template

[savitha-qs]

What this PR does / why we need it:

Addresses Issue 275

Checklist

• [x] Reviewed the CONTRIBUTING.md guide (required)
• [x] Verify the work you plan to merge addresses an existing issue (If not, open a new one) (required)
• [x] Check your branch with helm lint (required)
• [x] Update version in Chart.yaml according semver rules (required)
• [x] Substitute annotations section in Chart.yaml annotating implementations (useful for Artifecthub changelog) (required)
• [x] Update chart README using helm-docs (required)

Which issue(s) this PR fixes:

Fixes #<275>

Special notes for your reviewer:

[valeriano-manassero]

Checks looks good but there's still missing annotations as required in point 5 of 6

[savitha-qs]

@valeriano-manassero I've updated the annotation now. Let me know if it looks good. Thanks!

[savitha-qs]

@valeriano-manassero If this looks good to you, would you mind approving the PR? Or, feel free to merge it. Would appreciate it, thanks!