chore(Java): resolve `awssdk:core` dependency in TestVectors build.gradle.kts

[imabhichow]

Issue #, if available:

Description of changes:

• Remove software.amazon.awssdk:core:2.19.1 dependency from TestVectors build.gradle to sync with AwsCryptographicMaterialProviders build.gradle.
• The above dependency prevents the ESDK-Java pom.xml from pulling MPL TestVector.

Squash/merge commit message, if applicable:

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