Do not force maven.test.redirectTestOutputToFile=false on test runs

[jglick]

PCT build logs in, e.g., jenkinsci/bom#107 are gigantic. I do not really need to see the full output from every test. Would rather just see the names of tests being run, as https://github.com/jenkinsci/plugin-pom/blob/58a771dfab9e26ad2545875240022189a7db4af4/pom.xml#L1084-L1094 does. If a user really wants the full output, they should be able to readd this option in -mavenProperties, which from my reading of

plugin-compat-tester/plugins-compat-tester/src/main/java/org/jenkins/tools/test/maven/ExternalMavenRunner.java

Lines 35 to 38 in c3bcaa8

	for (Map.Entry<String,String> entry : config.userProperties.entrySet()) {
	cmd.add("--define=" + entry);
	}
	cmd.addAll(Arrays.asList(goals));

cannot be used to override properties defined here.

(I am leaving forkCount=1 alone for now, even though this is in fact the default in https://github.com/jenkinsci/plugin-pom/blob/58a771dfab9e26ad2545875240022189a7db4af4/pom.xml#L64-L65, since at least I normally override it to 1C in my local ~/.m2/settings.xml which would apply by default in PCT as well, perhaps to the detriment of reproducibility. But it is suspect too.)

[jglick]

Test failure looks like a flake:

Exception in thread "main" java.io.IOException: Unable to open file /mnt/agent-workspace/workspace/ries_plugin-compat-tester_PR-198/out/pct-report.xsl for writing.
	at org.codehaus.plexus.util.FileUtils.checkCanWrite(FileUtils.java:1240)
	at org.codehaus.plexus.util.FileUtils.copyStreamToFile(FileUtils.java:1212)
	at org.jenkins.tools.test.PluginCompatTester.testPlugins(PluginCompatTester.java:161)
	at org.jenkins.tools.test.PluginCompatTesterCli.main(PluginCompatTesterCli.java:157)

[jglick]

I am tempted to pass -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn by default (-ntp is better but presumes Maven 3.6.1+ which might be premature). But at least callers can add this for themselves already.