Continue updating previous generic dictionaries after expansion (#40355)

Continue updating previous generic dictionaries after expansion (#40355)

Fix perf regression after introduction of expandable generic
dictionaries. When we expand a generic dictionary, we should back
propagate the change to previously allocated shorter versions of
the same dictionary, otherwise already running JITted code may
continue referring to the "old version" of the dictionary implying
repeated slow path generic lookups.

Thanks

Tomas