Update pull request workflow to reuse centralized workflow

[MohamedSabthar]

Description

• Related issue: Migrating GitHub Workflows to the Central Ballerina Standard Library Repository ballerina-library#4778

Related Pull Requests (remove if not relevant)

• Pull request 1
• Pull request 2

One line release note:

• One line describing the feature/improvement/fix made by this PR

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

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Test Configuration:

• Ballerina Version:
• Operating System:
• Java SDK:

Checklist:

Security checks

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