fix custom folding regions end ignored end of comments are reached

[danthe1st]

What it does

In #2282, I implemented folding of custom regions if the start and end region markers are the same.
This stops processing when the last comment is reached. In that case, I forgot to ensure that all remaining open folding regions need to be created appropriately.

For example, consider the following reproducer:

• Enable extended folding (if disabled)
• Enable custom folding regions
• Set both the start and end region marker comments to ----- in Window > Preferences > Java > Editor > Folding
• Create the following class:

package org.example.test;

public class Repro {
	
	// ----- getters/setters -----

	public String test(boolean b) {
		if (b)
			
			return "a";
		return "b";
	}

}

The region for the // ----- getters/setters ----- comment is missing.

How to test

Use the reproducer above (or similar) and see that the region is present.

This is also included as a text case.

Author checklist

• I have thoroughly tested my changes
• The change is following the coding conventions
• I have signed the Eclipse Contributor Agreement (ECA)

[jjohnstn]

Looks good.