[eclipse-pmc] Add back an old method from 3.3 (detected as an API additi

[Olivier Thomann <Olivier_Thomann@xxxxxxxxxx>]

GOALS/BENEFITS:
- When converting JDT/Core to API tools, a method tagged as internal in an 
API class (org.eclipse.jdt.core.dom.AST) has been removed.
The tooling detected it. To correct the situation, the old method has been 
added back tagged with @noreference and @deprecated and an empty body.
This is now detected by the API freeze check.

AFFECTED BUGS:
- https://bugs.eclipse.org/bugs/show_bug.cgi?id=229526

RISKS:
- None. This method is not used. This comes back to the method signature 
that we had in 3.3.

PERFORMANCE IMPACTS:
- None.

Cordialement/Regards,

Frédéric