Upgrade to JUnit Jupiter 5.5.0-RC1

This commit also removes the workaround that required to exclude junit 4
explicitly now that a related issue in JUnit Jupiter has been fixed.

Closes gh-17266

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -6934,9 +6934,9 @@ useful libraries.
 
 [TIP]
 ====
-The starter also brings the vintage engine and `junit:junit` so that you can run both
-JUnit 4 and Junit 5 tests. If you have migrated your tests to JUnit 5, you should
-exclude JUnit 4 support, as shown in the following example:
+The starter also brings the vintage engine so that you can run both JUnit 4 and Junit 5
+tests. If you have migrated your tests to JUnit 5, you should exclude JUnit 4 support, as
+shown in the following example:
 
 [source,xml,indent=0,subs="verbatim,quotes,attributes"]
 ----
@@ -6949,10 +6949,6 @@ exclude JUnit 4 support, as shown in the following example:
 				<groupId>org.junit.vintage</groupId>
 				<artifactId>junit-vintage-engine</artifactId>
 			</exclusion>
-			<exclusion>
-				<groupId>junit</groupId>
-				<artifactId>junit</artifactId>
-			</exclusion>
 		</exclusions>
 	</dependency>
 ----
@@ -9030,8 +9026,7 @@ makes it possible to use `@BeforeClass` and `@AfterClass` annotations on non-sta
 methods, which is a good fit for Kotlin.
 
 JUnit 5 is the default and the vintage engine is provided for backward compatibility with
-JUnit 4. If you don't use it, exclude `org.junit.vintange:junit-vintage-engine` and
-`junit:junit`. See the
+JUnit 4. If you don't use it, exclude `org.junit.vintange:junit-vintage-engine`. See the
 {junit5-documentation}/#dependency-metadata-junit-jupiter-samples[JUnit 5 documentation]
 for more details. You also need to
 {junit5-documentation}/#writing-tests-test-instance-lifecycle-changing-default[switch test