Fix SubMonitor.convert() usage in Policy.subMonitorFor() methods

The previous implementation used SubMonitor.convert(monitor, ticks) which
internally calls beginTask(), causing "beginTask may only be called once"
errors when the returned monitor is passed to code that also calls beginTask().

The correct pattern is SubMonitor.convert(monitor).split(ticks), which creates
a child monitor without calling beginTask on it, allowing the caller to call
beginTask as needed.

This fixes test failures where FussyProgressMonitor detected multiple beginTask
calls (e.g., "beginTask may only be called once (old name=Opening 'MyProject'.)").

Files changed:
- resources/bundles/org.eclipse.core.resources/.../Policy.java
- team/bundles/org.eclipse.team.core/.../Policy.java
- team/bundles/org.eclipse.team.ui/.../Policy.java
- team/bundles/org.eclipse.jsch.core/.../Policy.java

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: vogella

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/utils/Policy.java

@@ -189,6 +189,6 @@ public static IProgressMonitor subMonitorFor(IProgressMonitor monitor, int ticks
 		if (monitor instanceof NullProgressMonitor) {
 			return monitor;
 		}
-		return new SubProgressMonitor(monitor, ticks);
+		return SubMonitor.convert(monitor).split(ticks);
 	}
 }

team/bundles/org.eclipse.jsch.core/src/org/eclipse/jsch/internal/core/Policy.java

@@ -38,7 +38,7 @@ public static IProgressMonitor subMonitorFor(IProgressMonitor monitor,
     if(monitor instanceof NullProgressMonitor){
       return monitor;
     }
-    return SubMonitor.convert(monitor, ticks);
+    return SubMonitor.convert(monitor).split(ticks);
   }
 
 }

team/bundles/org.eclipse.team.core/src/org/eclipse/team/internal/core/Policy.java

@@ -57,7 +57,7 @@ public static IProgressMonitor subMonitorFor(IProgressMonitor monitor, int ticks
 		if (monitor instanceof NullProgressMonitor) {
 			return monitor;
 		}
-		return SubMonitor.convert(monitor, ticks);
+		return SubMonitor.convert(monitor).split(ticks);
 	}
 
 	public static IProgressMonitor infiniteSubMonitorFor(IProgressMonitor monitor, int ticks) {

team/bundles/org.eclipse.team.ui/src/org/eclipse/team/internal/ui/Policy.java

@@ -72,7 +72,7 @@ public static IProgressMonitor subMonitorFor(IProgressMonitor monitor, int ticks
 		if (monitor instanceof NullProgressMonitor) {
 			return monitor;
 		}
-		return SubMonitor.convert(monitor, ticks);
+		return SubMonitor.convert(monitor).split(ticks);
 	}
 
 	public static IProgressMonitor monitorFor(IProgressMonitor monitor) {