#11285 Modified config service API response to return correct data type

[arishta]

Fixed issue: #11285

Describe changes proposed in this pull request:

• The server config API : config_service returns all values as strings, including boolean values (like 'true' or 'false'). These values had to be parsed in the frontend. This PR modifies the response to return the correct data type.

For more context, please refer the previously closed PR for this issue.
cBioPortal/cbioportal-frontend#5070

Testing

• Manually tested

As can be seen in the screenshot, the response includes the values as boolean (true/false) and not strings ("true"/"false").

Checks

• The commit log is comprehensible. It follows 7 rules of great commit messages. We can fix this during merge by using a squash+merge if necessary
• Has tests or has a separate issue that describes the types of test that should be created. If no test is included it should explicitly be mentioned in the PR why there is no test.
• Is this PR adding logic based on one or more clinical attributes? If yes, please make sure validation for this attribute is also present in the data validation / data loading layers (in backend repo) and documented in File-Formats Clinical data section!
• Make sure your PR has one of the labels defined in https://github.com/cBioPortal/cbioportal/blob/master/.github/release-drafter.yml

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[arishta]

Hi @inodb @alisman
Please review this fix for the issue: #11285.