[master] Fix runtime invokeAsync API to call function block the calling Thread

[warunalakshitha]

Purpose

Fixes https://github.com/ballerina-platform/ballerina-lang/issues/42865 Fixes https://github.com/ballerina-platform/ballerina-lang/issues/42868

Check List

• [x] Read the Contributing Guide
• [ ] Updated Change Log
• [ ] Checked Tooling Support (#<Issue Number>)
• [x] Added necessary tests
  • [x] Unit Tests
  • [ ] Spec Conformance Tests
  • [ ] Integration Tests
  • [ ] Ballerina By Example Tests
• [ ] Increased Test Coverage
• [ ] Added necessary documentation
  • [ ] API documentation
  • [ ] Module documentation in Module.md files
  • [ ] Ballerina By Examples