Cannot override manager implementation in Tomcat Webapps Deployer

[ashendes]

Description: It is not possible to change the session manager used by updating the configs in context.xml as the manager is always dynamically set to an instance of CarbonTomcatSessionManager in the deployer.

https://github.com/wso2/carbon-deployment/blob/6f84ce87ec8a3a8f39dc2df162cfa88a3932744f/components/webapp-mgt/org.wso2.carbon.webapp.mgt/src/main/java/org/wso2/carbon/webapp/mgt/TomcatGenericWebappsDeployer.java#L288-L297

For WSO2 Identity Server, there are no use cases which require webapps to be accessed in the same tenant context which deployed the app. Webapps should be accessible across tenants.

In the current implementation shown above, the CarbonTomcatSessionManager is explicitly set for webapps in the Super Tenant realm during deployment. Therefore, those webapps become accessible only from within Super Tenant context.