Eliminate hardcoded values

[lmatz]

If some of the hardcoded values should not be visible/tuned by users, we may introduce a [developer] section to the src/config/risingwave.toml or config them in a separate file to prevent misuse/confusion.

Just never know when the value needs to be changed to see how the performance changes, recompiling is slow in the release mode.

[lmatz]

• [x] DEFAULT_CHUNK_SIZE -> batch_chunk_size
• [x] HASH_AGG_CACHE_SIZE -> unsafe_agg_cache_size
• [x] JOIN_CACHE_CAP -> unsafe_join_cache_size
• [x] EXTREME_CACHE_SIZE -> unsafe_extreme_cache_size
• [x] PROCESSING_WINDOW_SIZE -> stream_chunk_size
• [x] K_PROCESSING_WINDOW_SIZE -> batch_chunk_size
• [ ] TOPN_CACHE_HIGH_CAPACITY_FACTOR
• [x] ENABLE_EXECUTOR_ROW_COUNT -> stream_enable_executor_row_count
• [ ] INDEX_BITS
• [ ] LOCAL_EXECUTE_BUFFER_SIZE
• [x] BOUNDED_BUFFER_SIZE
• [x] CONNECTOR_MESSAGE_BUFFER_SIZE
• [ ] ......

[BugenZhao]

By extracting the constants of streaming cache size, it'll also benifit #5080. 😄

[skyzh]

To contributors: one example of resolving this issue is: https://github.com/risingwavelabs/risingwave/pull/5361. It's just about moving variables to the config file. Welcome to have a try!

[lmatz]

Most important ones are done, the rest probably don't seem to have much impact, so we do it in the future if really necessary.