Remove redundant spring-plugin-core dependencies

Closes gh-18317

spring-boot-project/spring-boot-starters/spring-boot-starter-hateoas/pom.xml

@@ -23,9 +23,5 @@
 			<groupId>org.springframework.hateoas</groupId>
 			<artifactId>spring-hateoas</artifactId>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.plugin</groupId>
-			<artifactId>spring-plugin-core</artifactId>
-		</dependency>
 	</dependencies>
 </project>

spring-boot-project/spring-boot-test-autoconfigure/pom.xml

@@ -346,11 +346,6 @@
 			<artifactId>spring-hateoas</artifactId>
 			<scope>test</scope>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.plugin</groupId>
-			<artifactId>spring-plugin-core</artifactId>
-			<scope>test</scope>
-		</dependency>
 		<dependency>
 			<groupId>org.testcontainers</groupId>
 			<artifactId>junit-jupiter</artifactId>