[Improvement] Support CompressGtidSet when lastseenGtid exceeds special length

[gerayking]

To ensure Read-After-Write (RAW) consistency, vtgate internally maintains lastseengtid, which verifies that MySQL has executed the corresponding Data Manipulation Language (DML). However, the length of lastseengtid tends to increment continuously, thus necessitating the design of the CompressGtidset mechanism to prevent lastseengtid from becoming excessively long.

Currently, the CompressGtidset function is invoked passively through the broadcast protocol of the health check system. During instances of high concurrency, the length of lastseengtid may surge abruptly. Refer to the following links for additional information on RAW and CompressGtidSet.

Moving forward, the goal is to facilitate active data collection of the MySQL instance status and invoke CompressGtidset whenever the length of lastseengtid crosses a certain threshold.