Seagrass generates in frozen rivers

removes seagrass in frozen rivers

BE 1.21.101

The title is a bit incorrect is saying seagrass will generate in the frozen river, but this bug report ie saying not generate seagrass in the frozen river.

removing seagrass in frozen rivers to match java edition

in java edition, seagrass not generates in frozen rivers;

in bedrock edition, seagrass generates in frozen rivers

removes seagrass in bedrock edition