Reduce ACCOUNT_UPDATE_MAX_SIZE to 32 KiB

[partylikeits1983]

Related to #1464 and #1441

The ACCOUNT_UPDATE_MAX_SIZE limit was temporarily increased from 32 KiB to 256 KiB so that it would be possible to test the deployment of accounts which use MASM produced by the compiler.

The limit needs to be reduced back to 32 KiB once MAST serialization becomes more efficient.

[bobbinth]

We could maybe be more generous and bring it down to 64 KiB or something like that.