Fix style nit

Back to you for the test failure

https://build.bitcoinabc.org/buildConfiguration/BitcoinABC_BitcoinAbcStaging/845463?expandBuildDeploymentsSection=false&hideTestsFromDependencies=false&hideProblemsFromDependencies=false

Fix clang error

Cleanup locks

Feedback. Only cleanup cache once per block finalization.

Fix build failure and rebase

Address early feedback in https://reviews.bitcoinabc.org/D16992#inline-74171

Fix chainstate dependency

Pass peer manager down per feedback. This no longer black boxes the logic of the proof validity check and the testing is not significantly worse.

add MSG_UNDEFINED constant

In D16782#381036, @Fabien wrote:

I see your test doesn't check for contiguous heights, you should add that

Use lower_bound instead since it is more technically correct and robust to future changes. There is no change in behavior.

The patch looks ok but there is a test failure

changes per feedback to remove the cs_main lock. now depends on D16793