[test] junit show negative times for ClassFileReaderTest_1_8 tests

Negative times for org.eclipse.jdt.core.tests.compiler.regression.ClassFileReaderTest_1_8 - and only for that class.

For example I20240206-1800\eclipse-testing\results\ep431I-unit-win32-java17_win32.win32.x86_64_17\org.eclipse.jdt.core.tests.compiler.regression.TestAll.xml:

```
test001_classTypeParameter - 11 time="-1.707278660457E9"
test001_classTypeParameter - 17 time="-1.707278861728E9"
test001a_classTypeParameterDifferingRetentions - 11 time="-1.707278660457E9"
test001a_classTypeParameterDifferingRetentions - 17 time="-1.707278861728E9"
test002_methodTypeParameter - 11 time="-1.707278660473E9"
test002_methodTypeParameter - 17 time="-1.707278861743E9"
test003_classExtends - 11 time="-1.707278660473E9"
test003_classExtends - 17 time="-1.707278861743E9"
test004_classExtends - 11 time="-1.707278660488E9"
test004_classExtends - 17 time="-1.707278861759E9"
test005_classTypeParameterBound - 11 time="-1.707278660504E9"
test005_classTypeParameterBound - 17 time="-1.707278861775E9"
test006_methodTypeParameterBound - 11 time="-1.707278660504E9"
test006_methodTypeParameterBound - 17 time="-1.707278861775E9"
test007_field - 11 time="-1.70727866052E9"
test007_field - 17 time="-1.70727886179E9"
test008_methodReturn - 11 time="-1.70727866052E9"
test008_methodReturn - 17 time="-1.70727886179E9"
test009_methodReceiver - 11 time="-1.707278660535E9"
test009_methodReceiver - 17 time="-1.707278861806E9"
test010_methodFormalParameter - 11 time="-1.707278660535E9"
test010_methodFormalParameter - 17 time="-1.707278861822E9"
test011_throws - 11 time="-1.707278660551E9"
test011_throws - 17 time="-1.707278861822E9"
test012_annotationMethodReturn - 11 time="-1.707278660551E9"
test012_annotationMethodReturn - 17 time="-1.707278861837E9"
testBug548596 - 11 time="-1.707278660567E9"
testBug548596 - 17 time="-1.707278861837E9"
```

Start with the reported TestAll.xml output and the org.eclipse.jdt.core.tests.compiler.regression.ClassFileReaderTest_1_8 test class, comparing its timing entries with other test classes. Trace how these test results are produced and verify that the affected tests report valid, non-negative times without changing their test outcomes.

Written by the indexing model from the issue text.