[2.1.x] Fix OpenAPI spec generation issues for U10 patch

[lnash94]

Purpose

Fixes:

1. Fixed included record field overriding issue https://github.com/wso2-enterprise/internal-support-ballerina/issues/831
2. Improvement: mapping constant values as default value in the generated OAS Support constant value expression for the default value mapping in OAS generation ballerina-library#7353

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[sonarqubecloud]

Quality Gate passed

Issues
5 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[TharmiganK]

LGTM

[HindujaB]

This fix will be released with 2201.10.3 patch
ballerina-platform/ballerina-distribution#5823