Replace com.ibm.icu dependency with org.eclipse.ant.core in expression

[vogella]

tests

The ExpressionTestsPluginUnloading test was using com.ibm.icu bundle for testing plugin loading/unloading and classloader isolation. This change replaces it with org.eclipse.ant.core bundle to support removal of com.ibm.icu from the platform.

Changes:

• Replace fake com.ibm.icu.text.DecimalFormat with org.eclipse.ant.core.AntRunner
• Update test to use org.eclipse.ant.core bundle instead of com.ibm.icu
• Adjust instanceof checks to match new bundle's class interfaces
• org.eclipse.ant.core is a suitable replacement as it can be safely stopped/restarted without affecting test execution

[github-actions[bot]]

Test Results

 1 953 files  ±0   1 953 suites  ±0   1h 31m 42s ⏱️ + 7m 3s  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 e4b0f528. ± Comparison against base commit b0bbf457.

[merks]

Of course I have nothing again this change to a test.

There are some actual uses outside of test: