Redo examples that used COVID data

[MaryamZi]

Current Limitation

$title.

Suggested Improvement

At least

• https://ballerina.io/learn/work-with-data-using-queries-in-ballerina/ - @gimantha
• https://ballerina.io/learn/write-a-restful-api-with-ballerina/ - @TharmiganK @NipunaRanasinghe
• https://ballerina.io/learn/write-a-graphql-api-with-ballerina/ - @ThisaruGuruge @NipunaRanasinghe

Version

No response

[TharmiganK]

@MaryamZi Is this issue created to update the code with the latest Ballerina version changes? Or do you expect a content revamp?

[MaryamZi]

@MaryamZi Is this issue created to update the code with the latest Ballerina version changes? Or do you expect a content revamp?

Sorry, should've described the change. It is to redo the content with some other example/scenario, instead of basing it on COVID scenarios/data.