Fix erratic test failure in DiagnosticsTest

This commit fixes:
```
org.eclipse.core.internal.resources.ResourceException: Problems
encountered while deleting resources.
	at org.eclipse.core.internal.resources.Resource.delete(Resource.java:816)
	at org.eclipse.core.internal.resources.Resource.delete(Resource.java:772)
	at org.eclipse.lsp4e.test.diagnostics.DiagnosticsTest.testDiagnosticsForMarkerUpdateAfterDeletedFile(DiagnosticsTest.java:192)
Contains: Could not delete
'D:\junit-workspace\DiagnoticsTest1714763955417\test1714763955426.lspt'.
org.eclipse.core.runtime.CoreException: Could not delete:
D:\junit-workspace\DiagnoticsTest1714763955417\test1714763955426.lspt.
	at org.eclipse.core.internal.filesystem.local.LocalFile.delete(LocalFile.java:161)
	at org.eclipse.core.internal.resources.ResourceTree.internalDeleteFile(ResourceTree.java:315)
	at org.eclipse.core.internal.resources.ResourceTree.standardDeleteFile(ResourceTree.java:801)
	at org.eclipse.core.internal.resources.Resource.unprotectedDelete(Resource.java:1826)
	at org.eclipse.core.internal.resources.Resource.delete(Resource.java:803)
	at org.eclipse.core.internal.resources.Resource.delete(Resource.java:772)
	at org.eclipse.lsp4e.test.diagnostics.DiagnosticsTest.testDiagnosticsForMarkerUpdateAfterDeletedFile(DiagnosticsTest.java:192)
Caused by: java.nio.file.FileSystemException:
D:\junit-workspace\DiagnoticsTest1714763955417\test1714763955426.lspt:
The process cannot access the file because it is being used by another
process
	at java.base/sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:92)
	at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:103)
	at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:108)
	at java.base/sun.nio.fs.WindowsFileSystemProvider.implDelete(WindowsFileSystemProvider.java:275)
	at java.base/sun.nio.fs.AbstractFileSystemProvider.deleteIfExists(AbstractFileSystemProvider.java:110)
	at java.base/java.nio.file.Files.deleteIfExists(Files.java:1191)
	at org.eclipse.core.internal.filesystem.local.LocalFile.internalDelete(LocalFile.java:242)
	at org.eclipse.core.internal.filesystem.local.LocalFile.delete(LocalFile.java:159)
	... 64 more
```

org.eclipse.lsp4e.test/src/org/eclipse/lsp4e/test/diagnostics/DiagnosticsTest.java

@@ -191,8 +191,8 @@ public void testDiagnosticsForMarkerUpdateAfterDeletedFile() throws CoreExceptio
 		Job[] allMarkerJobs = Job.getJobManager().find(LanguageServerPlugin.FAMILY_UPDATE_MARKERS);
 		assertThat(allMarkerJobs.length, is(1));
 		Job markerJob = allMarkerJobs[0];
-		file.delete(true, null);
-		waitForAndAssertCondition(1_000, () -> {
+		waitForAndAssertCondition(2_000, () -> {
+			file.delete(true, null);
 			assertEquals(file.exists(), false);
 			return true;
 		});