[Enhancement][FLINK-28959][Stream] 504 gateway timeout when consume large number of topics using TopicPatten

[futeng]

Our situation is as follows:

• In a single namespace, more than 300 topics(partitioned-topic with a single partition) will report this error;
• Error still exists after resource expansion
• A flick client program consumes 30 to 50 topics per program. This error is bound to be reported after five consecutive programs

Version

• flink-sql-connector-pulsar: 1.15.0.1
• pulsar 2.9.2.17

[syhily]

Yep, this is a performance issue. We need extra discussion.

[syhily]

Fixed in #222