revert: "build: fix JaCoCo report generation."

This change breaks the unit tests:
[ERROR] org.apache.maven.surefire.booter.SurefireBooterForkException: The forked VM terminated
without properly saying goodbye. VM crash or System.exit called?
[ERROR] Command was /bin/sh -c cd /home/travis/build/php-coder/mystamps &&
/usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java '@{argLine}' -Dfile.encoding=UTF-8 -Xss256k -jar
/home/travis/build/php-coder/mystamps/target/surefire/surefirebooter8389137149183507179.jar
/home/travis/build/php-coder/mystamps/target/surefire 2020-01-22T23-14-08_793-jvmRun1
surefire4311161623250613262tmp surefire_02177420687972276735tmp

This reverts commit 7fbb2f6.

Fix #1243

Author: php-coder

pom.xml

@@ -916,10 +916,8 @@
 						Workaround for a bug in surefire plugin: it doesn't respect sourceEncoding
 						and doesn't pass it into a forked process.
 						See: https://stackoverflow.com/questions/17656475/maven-source-encoding-in-utf-8-not-working
-						
-						NB: @{argLine} is needed for JaCoCo java agent.
 					-->
-					<argLine>@{argLine} -Dfile.encoding=${project.build.sourceEncoding} -Xss256k</argLine>
+					<argLine>-Dfile.encoding=${project.build.sourceEncoding} -Xss256k</argLine>
 				</configuration>
 			</plugin>