Make normalization more aggressive

[jackysp]

Enhancement

If, for example, the digest of insert into t values (1, 1), (2,2) is different from that of insert into t values (1, 1), then they will be treated as different statements in the statements summary. This can easily lead to meaningful SQL being eliminated. We should make the digests of trail inserts with different row counts the same.

[xhebox]

I've tested a little bit, this does fixed digest_test, but did not improve #33559