Vreplication fails when gtid_executed is > 10000 bytes

[gtowey]

Overview of the Issue

Vreplication fails with unable to parse mysql 5.6 GTID set when the length of the gtid_executed string exceeds the column size of 10,000 bytes.

Note: This is a pretty simple fix and I can submit a PR along with this issue.

Reproduction Steps

1. Create a large gtid_executed set by performing many replication changes across many mysql instances with different server UUIDs
2. Run a Reshard workflow
3. View the error in vreplication on the chosen tablet's status page.

Operating system and Environment details

n/a

[shlomi-noach]

@gtowey I assume the problem is here:

vitess/go/vt/binlog/binlogplayer/binlog_player.go

Lines 544 to 545 in 600cca7

	pos VARBINARY(10000) NOT NULL,
	stop_pos VARBINARY(10000) DEFAULT NULL,

?

If you are able to, we welcome a PR to increase this length.

[mattlord]

I'm going to close this as done for now. Please note that we've since added compression for this value as well: #7877