Changes to make OS and PG fields optional for managed setup

[sandhi18]

🔩 Description: What code changed, and why?

Added the changes to make the OS instance count and OS instance type along with PG instance count and PG instance type as optional for the managed setup.
These changes are applicable for both AWS and Onprem setup

⛓️ Related Resources

https://chefio.atlassian.net/browse/CHEF-3206

👍 Definition of Done

• AWS Managed setup should be successful without providing the OS and PG instance count and type
• Onprem Managed setup should be successful without providing the OS and PG instance count and type

👟 How to Build and Test the Change

✅ Checklist

All PRs must tick these:

• I have read the CONTRIBUTING document.
• All commits signed-off for the Developer Certification of Origin.

With occasional exceptions, all PRs from Progress employees must tick these:

• Is the code clear? (complicated code or lots of comments--subdivide and use well-named methods, meaningful variable names, etc.)
• Consistency checked? (user notifications, user prompts, visual patterns, code patterns, variable names)
• Repeated code blocks eliminated? (adapt and reuse existing components, blocks, functions, etc.)
• Spelling, grammar, typos checked? (at a minimum use make spell in any component directory)
• Code well-formatted? (indents, line breaks, etc. improve rather than hinder readability)

All PRs from Progress employees should tick these if appropriate:

• Tests added/updated? (all new code needs new tests)
• Docs added/updated? (all customer-facing changes)

Please add a note next to any checkbox above if you are NOT ticking it.

📷 Screenshots, if applicable

https://progresssoftware.sharepoint.com/:v:/s/ChefCoreC/Eecj8a3gf95Pq0HukGrgmOIBc6spTJgeuU9o1R6zfuvVkA?e=UXRHYS

https://progresssoftware.sharepoint.com/:v:/s/ChefCoreC/ESjqnymm8FtLqTPdpQHEd7oBSIBwcegWZWJ99ouo8RuyXQ?e=4CsqFk

[netlify]

👷 Deploy Preview for chef-automate processing.

Name	Link
🔨 Latest commit	380a6c3
🔍 Latest deploy log	https://app.netlify.com/sites/chef-automate/deploys/6479cc0b82dc5500086ca053

[sonarqube-for-infrastructure-prod]

SonarQube Quality Gate

Maintainability Rating on New Code (is worse than A)
0.0% Coverage on New Code (is less than 80%)

See analysis details on SonarQube

Fix issues before they fail your Quality Gate with SonarLint in your IDE.