Deprecate Throwables.propagate with RuntimeException in EmbeddedChannels.java

Guava "Throwables.propagate" is deprecated. see reasons in
https://github.com/google/guava/wiki/Why-we-deprecated-Throwables.propagate

This JIRA modifies core/common/src/test/java/alluxio/EmbeddedChannels.java to replace

or

with

Remember also to remove the corresponding import if Throwables becomes unused