Fix sms template update issues in root orgs and sub orgs

[SujanSanjula96]

Purpose

Fixes SMS template update issues in root org and sub orgs. From this PR, SMS template retrieval logic is updated as follows.

1. First get the org template directly. (This is needed to decide whether POST or PUT call needs for the update)
2. If it is not found, inherit from parent for sub orgs and get the system template for root orgs.

Related Issues

• SMS template update issues in root orgs and sub orgs product-is#22322

Related PRs

• N/A

Checklist

• e2e cypress tests locally verified. (for internal contributers)
• Manual test round performed and verified.
• UX/UI review done on the final implementation.
• Documentation provided. (Add links if there are any)
• Relevant backend changes deployed and verified
• Unit tests provided. (Add links if there are any)
• Integration tests provided. (Add links if there are any)

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines
• Ran FindSecurityBugs plugin and verified report
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets

[pavinduLakshan]

Please add changeset too.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.04%. Comparing base (dca7d1c) to head (c73af2c).
Report is 15 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7345   +/-   ##
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  Coverage   36.04%   36.04%           
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  Files          42       42           
  Lines         899      899           
  Branches      205      205           
=======================================
  Hits          324      324           
  Misses        575      575           

Flag	Coverage Δ
@wso2is/core	36.04% <ø> (ø)

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[wso2-jenkins-bot]

🦋 Changeset detected

The changes in this PR will be included in the next version bump.

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