Remove dependency management for Gradle that is no longer used

spring-boot-dependencies/pom.xml

@@ -78,7 +78,6 @@
 		<freemarker.version>2.3.25-incubating</freemarker.version>
 		<elasticsearch.version>2.4.4</elasticsearch.version>
 		<glassfish-el.version>3.0.0</glassfish-el.version>
-		<gradle.version>3.4</gradle.version>
 		<groovy.version>2.4.10</groovy.version>
 		<gson.version>2.8.0</gson.version>
 		<h2.version>1.4.194</h2.version>

spring-boot-parent/pom.xml

@@ -199,51 +199,6 @@
 				<artifactId>aether-util</artifactId>
 				<version>${aether.version}</version>
 			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-base-services</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-base-services-groovy</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-core</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-language-java</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-language-jvm</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-maven</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-platform-jvm</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-plugins</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
-			<dependency>
-				<groupId>org.gradle</groupId>
-				<artifactId>gradle-process-services</artifactId>
-				<version>${gradle.version}</version>
-			</dependency>
 			<dependency>
 				<groupId>org.jetbrains.kotlin</groupId>
 				<artifactId>kotlin-runtime</artifactId>