Fix crash when processing PostgreSQL packets in weird order

[iamnotacake]

• Clear pendingParse after receiving ParseComplete
• Clear pendingBind (sensitive data inside) after receiving BindComplete
• Clear pendingBind (set to nil) after receiving ReadyForQuery

Also, tiny fix in integration tests so DEBUG_LOG=False env var will really make AcraServer logs less verbose.

Checklist

• [ ] ~Change is covered by automated tests~ The bug that was fixed here only happens with Rust postgres driver, manually ensured it does not reproduce any more
• [x] The coding guidelines are followed
• [x] ~Public API has proper documentation in the Acra documentation site or has PR on documentation repository with new changes~
• [x] ~CHANGELOG.md is updated (in case of notable or breaking changes)~
• [x] CHANGELOG_DEV.md is updated
• [x] ~Benchmark results are attached (if applicable)~
• [x] ~Example projects and code samples are up-to-date (in case of API changes)~

[vixentael]

shouldn't we use mutex anywhere?

[Lagovas]

shouldn't we use mutex anywhere?

mutexes should be used to synchronize access to shared objects. Here is data related to 2 connections (app <> acra, acra <> db), and handled by 2 goroutines. If 2 goroutines change/update same data - then we should. If only one of them touches data at same time - then we shouldn't. For example if we touch data related to client's side packets in goroutine that work with client side connection, then we can omit mutexes because of opposite goroutine will not touch same data/buffers/processes.