General update for services to be Central-Instance compatible

Changes to pom.xml

1. Add new digit nexus repo under <repositories> tag

   <repository>
   <id>repo.digit.org</id>
   <name>eGov DIGIT Releases Repository</name>
   <url>https://nexus-repo.digit.org/nexus/content/repositories/snapshots/</url>
   </repository>

2. Add Tracer 2.1.0

   <dependency>
     <groupId>org.egov.services</groupId>
     <artifactId>tracer</artifactId>
     <version>2.1.0-SNAPSHOT</version>
   </dependency>

3. The host of the MDMS services referred by any service should be changed to the internal gateway host for tenant-based(namespace) redirection. Since multiple MDMS services will be running each for the different namespaces (schemas).

     - name: EGOV_MDMS_HOST
       valueFrom:
         configMapKeyRef:
           name: egov-service-host
           key: internal-gateway

4. { ADD if any new configs }