Throw IAE if suggest results return differently sized results.

If the term suggester is used the results are merged depending on
the number of terms produced by the tokenizer / tokenfilter. If a
term suggester is executed across multiple indices that share the
same field but with different analysis chains we can't merge the
result anymore sicne tokens are our of order or have a different size.

This commit throws ESIllegalArgumentException if the number of entries
are not the same across all results.

Closes #3196