Update deployment code for Diagnostic Settings

[senavar]

Change

Update code for Diagnostic Settings deployment for more simplified approach

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update (Wiki)

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (readme)
• I did format my code

Pipelines were ran for the storage account, SQL DB, and Log Analytics modules from PR #765

Wiki has been updated already to reflect this change: https://github.com/Azure/ResourceModules/wiki/ModulesDesign#diagnostic-settings