When performing a search operation in the FindReplaceLogic, it currently
always validates compatibility of the search options. In particular,
having incremental search and regex search enabled at the same time will
result in search operations not being performed. This results in
problems when performing replace operations that also include search
operations, as the search operation will not be executed then.

With this change, the search operations performed while doing a replace
will not validate the search operations but always perform the requested
search instead.

Fixes https://github.com/eclipse-platform/eclipse.platform.ui/issues/2203