Allow to set INI values in session tests

[HeikoKlare]

The JUnit 3 ConfigurationSessionTestSuite allows to set/change INI values for the configuration of an execution session. This capability is currently missing in the JUnit 5 SessionTestExection and the respective CustomSessionConfiguration. This change adds it.

This is necessary for:

• Migrate EclipseStarterConfigIniTest to JUnit 5 eclipse-equinox/equinox#1225

[eclipse-platform-bot]

This pull request changes some projects for the first time in this development cycle.
Therefore the following files need a version increment:

runtime/tests/org.eclipse.core.tests.harness/META-INF/MANIFEST.MF

An additional commit containing all the necessary changes was pushed to the top of this PR's branch. To obtain these changes (for example if you want to push more changes) either fetch from your fork or apply the git patch.

Git patch

From 08092490fbf4fd333b221bfdcf45b690b717a5f1 Mon Sep 17 00:00:00 2001
From: Eclipse Platform Bot <platform-bot@eclipse.org>
Date: Thu, 11 Dec 2025 17:34:28 +0000
Subject: [PATCH] Version bump(s) for 4.39 stream


diff --git a/runtime/tests/org.eclipse.core.tests.harness/META-INF/MANIFEST.MF b/runtime/tests/org.eclipse.core.tests.harness/META-INF/MANIFEST.MF
index 4e51573433..ed67d89930 100644
--- a/runtime/tests/org.eclipse.core.tests.harness/META-INF/MANIFEST.MF
+++ b/runtime/tests/org.eclipse.core.tests.harness/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: Eclipse Core Tests Harness
 Bundle-SymbolicName: org.eclipse.core.tests.harness;singleton:=true
-Bundle-Version: 3.17.400.qualifier
+Bundle-Version: 3.17.500.qualifier
 Bundle-Vendor: Eclipse.org
 Export-Package: org.eclipse.core.tests.harness;version="2.0",
  org.eclipse.core.tests.harness.session,
-- 
2.52.0

Further information are available in Common Build Issues - Missing version increments.

[github-actions]

Test Results

 1 953 files  ±0   1 953 suites  ±0   1h 20m 40s ⏱️ - 14m 27s
 4 744 tests ±0   4 720 ✅ ±0   24 💤 ±0  0 ❌ ±0 
14 232 runs  ±0  14 050 ✅ ±0  182 💤 ±0  0 ❌ ±0 

Results for commit 1edef48. ± Comparison against base commit 72cce17.

♻️ This comment has been updated with latest results.