CompactionJob::Install(): fix log truncation (#8563)

Summary:
event log info may be truncated, the default buffer size is 512, this PR changes buffer size to 8192.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8563

Reviewed By: ajkr

Differential Revision: D29838229

Pulled By: jay-zhuang

fbshipit-source-id: 00c5dea3caff0641a209f02c972e92d65b505f50

db/compaction/compaction_job.cc

@@ -879,7 +879,7 @@ Status CompactionJob::Install(const MutableCFOptions& mutable_cf_options) {
 
   UpdateCompactionJobStats(stats);
 
-  auto stream = event_logger_->LogToBuffer(log_buffer_);
+  auto stream = event_logger_->LogToBuffer(log_buffer_, 8192);
   stream << "job" << job_id_ << "event"
          << "compaction_finished"
          << "compaction_time_micros" << stats.micros