Update entire Gradle Wrapper package

[shshashwat]

Problem description
The current gradle upgrade only upgrades the gradle version but not the entire package. With gradle version upgrade entire package should be updated.

Problem location
https://github.com/pravega/schema-registry/tree/master/gradle

Suggestions for an improvement
Run command gradle wrapper which will update entire gradle package. While performing this there will be significant changes needed on build.gradle.