[c00ler]

This change is a follow-up for changes in #3247.

The issue is that getStatisticsFile() uses getConfigChecksum(), which relies on potentially mutable values such as system properties, provider properties, etc. getStartupReportConfiguration() is called from the context that changes the state of system properties:

maven-surefire/maven-surefire-common/src/main/java/org/apache/maven/plugin/surefire/AbstractSurefireMojo.java

Line 1356 in ff6b6e3

createCopyAndReplaceForkNumPlaceholder(effectiveProperties, 1).copyToSystemProperties();

. Due to that, the value returned by getStatisticsFile() is different from the value stored in the RunOrderParameters. This change ensures that the statistics filename is calculated only once and reused.

Following this checklist to help us incorporate your
contribution quickly and easily:

• Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Run mvn clean install to make sure basic checks pass. A more thorough check will
  be performed on your pull request automatically.
• You have run the integration tests successfully (mvn -Prun-its clean install).

If your pull request is about ~20 lines of code you don't need to sign an
Individual Contributor License Agreement if you are unsure
please ask on the developers list.

To make clear that you license your contribution under
the Apache License Version 2.0, January 2004
you have to acknowledge this by using the following check-box.

• I hereby declare this contribution to be licenced under the Apache License Version 2.0, January 2004

• In any other case, please file an Apache Individual Contributor License Agreement.

[olamy]

LGTM.
Would you mind rebase this with last master changes (sorry there was a failure) as is we will have full build running for the PR.
Thanks

[olamy]

@c00ler All merged. Thanks for your contribution,
I will cherry-pick to 3.5.x branch