When placing a design block without keeping annotations, ClearAnnotation was
called before AnnotateSymbols, setting all references to "R?" form. This
caused AppendMultiUnitSymbol to skip building locked groups (it returns early
for unannotated refs), leaving the locked group map empty. Without locked
groups, the position-based annotation algorithm could assign units from
different multi-unit symbols to the same reference designator when symbols
shared the same value and lib symbol.
This preserves original annotations when auto-annotation is enabled, and
passes aResetAnnotation=true to AnnotateSymbols so it builds correct locked
groups from the original refs before resetting and reannotating.
When auto-annotation is disabled, ClearAnnotation is still called so the user
sees unannotated symbols as expected.
Fixes https://gitlab.com/kicad/code/kicad/-/issues/23183
Seth Hillbrand
208258d935