Remove dependency management for jetty-jsp as it does not exist

Jetty 9.3 no longer has a jetty-jsap artifact and dependency
management for it was removed in ff602e6. It was inadvertently
reintroducved in b303b3f. This commit removes it again.

See gh-5290
See gh-5825

spring-boot-dependencies/pom.xml

@@ -1546,17 +1546,6 @@
 				<artifactId>jetty-io</artifactId>
 				<version>${jetty.version}</version>
 			</dependency>
-			<dependency>
-				<groupId>org.eclipse.jetty</groupId>
-				<artifactId>jetty-jsp</artifactId>
-				<version>${jetty.version}</version>
-				<exclusions>
-					<exclusion>
-						<groupId>org.eclipse.jetty.orbit</groupId>
-						<artifactId>javax.servlet</artifactId>
-					</exclusion>
-				</exclusions>
-			</dependency>
 			<dependency>
 				<groupId>org.eclipse.jetty</groupId>
 				<artifactId>apache-jstl</artifactId>