Update ops limit in TxQueueLimiter every time we try adding tx.

[dmkozh]

Description

This is how the limiter has worked before the refactoring.

I somehow convinced myself that we reset limiter on upgrades, but that's not true. So for simplicity I just update the limit to make sure we always have up-to-date ops limit.

Checklist

• Reviewed the contributing document
• Rebased on top of master (no merge commits)
• Ran clang-format v8.0.0 (via make format or the Visual Studio extension)
• Compiles
• Ran all tests
• If change impacts performance, include supporting evidence per the performance document

[MonsieurNicolas]

r+ 8c5f3a0