benchmark the CheckTx after adding the mempool mutexes in core

[rach-id]

After implementing celestiaorg/celestia-core#1582 and depending on it in #4197, we should benchmark the CheckTx to how much delay is being added with the new mutexes.

This issue blocks the v3.2.1 release.

[evan-forbes]

to be extra specific, the main concern we have is with rechecktx. If the mempool is very large and we're blocking memool access the entire time, then it could block proposers from reaping from the mempool to create a block.

[rach-id]

After running the benchmarks under app/benchmarks using the recheck type, we found out that for msg send, for example, rechecking an 8mb block takes ~2s, which is good. So, we can close this issue