[JENKINS-66759] Regroup some modules in the same plugin

[Vlatombe]

Some calls in aws-java-sdk-core require the corresponding classes (from
aws-java-sdk-sts or aws-java-sdk-s3) to be in the same classloader.

• https://github.com/aws/aws-sdk-java/blob/59759680facd95c304ff5ce970fd62cb9eae87c2/aws-java-sdk-core/src/main/java/com/amazonaws/auth/profile/internal/securitytoken/STSProfileCredentialsServiceProvider.java#L53 requires aws-java-sdk-sts to be in the same classloader as aws-java-sdk-core.
• https://github.com/aws/aws-sdk-java/blob/59759680facd95c304ff5ce970fd62cb9eae87c2/aws-java-sdk-core/src/main/java/com/amazonaws/auth/SignerFactory.java#L45 requires aws-java-sdk-s3 to be in the same classloader as aws-java-sdk-core.

Also noting

• https://github.com/aws/aws-sdk-java/blob/59759680facd95c304ff5ce970fd62cb9eae87c2/aws-java-sdk-core/src/main/java/com/amazonaws/metrics/AwsSdkMetrics.java#L619 which could require aws-java-sdk-cloudwatchmetrics, however I'm not aware of any plugin using it at the moment. Could be reconsidered later.

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