[FLINK-36332] make depend-on-okhttp4 active by default.

```
mvn   help:all-profiles  | grep http
  Profile Id: depend-on-okhttp4 (Active: true , Source: pom)
```

```
mvn   help:all-profiles -Dfabric8.httpclient.impl=jdk -P \!depend-on-okhttp4  | grep http
  Profile Id: depend-on-okhttp4 (Active: false , Source: pom)
```

Author: SamBarker

pom.xml

@@ -196,10 +196,7 @@ under the License.
         <profile>
             <id>depend-on-okhttp4</id>
             <activation>
-                <property>
-                    <name>fabric8.httpclient.impl</name>
-                    <value>okhttp</value>
-                </property>
+                <activeByDefault>true</activeByDefault>
             </activation>
             <dependencies>
                 <dependency>