Modernize/simplify JUnit Gradle configuration (#2325)

Author: trask

buildSrc/src/main/kotlin/otel.java-conventions.gradle.kts

@@ -147,10 +147,11 @@ dependencies {
 
 testing {
   suites.withType(JvmTestSuite::class).configureEach {
+    useJUnitJupiter("5.13.4")
+
     dependencies {
       implementation(project())
 
-      implementation(enforcedPlatform("org.junit:junit-bom:5.14.1"))
       implementation(enforcedPlatform("org.testcontainers:testcontainers-bom:2.0.2"))
       implementation(enforcedPlatform("com.google.guava:guava-bom:33.5.0-jre"))
       implementation(enforcedPlatform("com.linecorp.armeria:armeria-bom:1.34.0"))
@@ -159,16 +160,11 @@ testing {
       compileOnly("com.google.errorprone:error_prone_annotations")
       compileOnly("com.google.code.findbugs:jsr305")
 
-      implementation("org.junit.jupiter:junit-jupiter-api")
-      implementation("org.junit.jupiter:junit-jupiter-params")
       implementation("org.mockito:mockito-core")
       implementation("org.mockito:mockito-junit-jupiter")
       implementation("org.assertj:assertj-core")
       implementation("org.awaitility:awaitility")
       implementation("io.github.netmikey.logunit:logunit-jul")
-
-      runtimeOnly("org.junit.jupiter:junit-jupiter-engine")
-      runtimeOnly("org.junit.platform:junit-platform-launcher")
     }
   }
 }