fix: Remove sdk2 from release branch, maintained in sdk2-snapshot branch (#124)

Removed the sdk2 directory from the release branch. All changes to sdk2 are backed up in the sdk2-snapshot branch: https://github.com/aws/aws-dynamodb-encryption-java/tree/skd2-snapshot

Author: acioc

pom.xml

@@ -23,7 +23,6 @@
       <module>ddej-build-tools</module>
       <module>common</module>
       <module>sdk1</module>
-      <module>sdk2</module>
       <module>examples</module>
   </modules>