[Release 3.0] Update `com.github.johnrengelman.shadow` to `com.gradleup.shadow` in gradle plugin

[peterzhuamazon]

[Release 3.0] Update com.github.johnrengelman.shadow to com.gradleup.shadow in gradle plugin.

Recently johnrengelman.shadow has been transfered to gradleup.shadow, and newer versions of the plugin cannot be obtained on the old namespace anymore:

• Future home/support for Shadow? GradleUp/shadow#908 (comment)
• https://github.com/GradleUp/shadow/releases/tag/8.3.0

This means for a lot of the OpenSearch Plugins, on main/3.0 specifically, they need to update their build.gradle with changes like this:

• [Release 3.0] Update common-utils shadow plugin repo and bump to 3.0.0.0-alpha1 common-utils#775

Or they will see below issues:

* What went wrong:
A problem occurred evaluating project ':alerting-spi'.
> Failed to apply plugin 'com.github.johnrengelman.shadow'.
   > Configuration with name 'shadow' not found.

or

* What went wrong:
A problem occurred evaluating root project 'common-utils'.
> Could not find method shadowJar() for arguments [build_6j3x90usouen452sgho5nghbu$_run_closure11@3ca6e6bf] on root project 'common-utils' of type org.gradle.api.Project.

Thanks.