Drop RxJava 2

RxJava 2 is end-of-life as of February 28, 2021. `ReactiveTestUtils` can
probably be dropped for 5.6 in favor of `Reactive3TestUtils`.

Author: rschmitt

httpcore5-testing/pom.xml

@@ -60,11 +60,6 @@
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
     </dependency>
-    <dependency>
-      <groupId>io.reactivex.rxjava2</groupId>
-      <artifactId>rxjava</artifactId>
-      <version>${rxjava.version}</version>
-    </dependency>
     <dependency>
       <groupId>io.reactivex.rxjava3</groupId>
       <artifactId>rxjava</artifactId>
@@ -161,4 +156,4 @@
     </plugins>
   </reporting>
 
-</project>
+</project>

httpcore5-testing/src/main/java/org/apache/hc/core5/testing/reactive/ReactiveTestUtils.java

@@ -78,7 +78,6 @@
     <mockito.version>4.11.0</mockito.version>
     <slf4j.version>1.7.36</slf4j.version>
     <log4j.version>2.25.0</log4j.version>
-    <rxjava.version>2.2.21</rxjava.version>
     <rxjava3.version>3.1.10</rxjava3.version>
     <testcontainers.version>1.21.3</testcontainers.version>
     <api.comparison.version>5.3</api.comparison.version>
@@ -382,4 +381,4 @@
     </plugins>
   </reporting>
 
-</project>
+</project>