Merge #7449: refactor: clean up governance inv tests after request cache removal

2673240 test: extract AssertMisbehaviorScore helper in governance inv tests (PastaClaw)
a8f2711 refactor(governance): move RELIABLE_PROPAGATION_TIME next to its only uses (PastaClaw)
83d8dd7 test: drop the governance inv fixture setup left over from CheckAndRemove (PastaClaw)
97abde6 test: reuse the peer helper in per_object_vote_sync_is_fulfilled_request_limited (PastaClaw)

Pull request description:

  ## What was done?

  Follow-up to #7442 and knst's review:

  - reuse the existing `MakeGovernanceInvPeer` helper in `per_object_vote_sync_is_fulfilled_request_limited`
  - remove the stale scheduler/thread/meta-manager fixture setup left behind when the `CheckAndRemove` tests were deleted
  - update the fixture comments to describe the remaining sync and mock-time requirements
  - extract an `AssertMisbehaviorScore` helper to remove repetitive state-stat assertions
  - move `RELIABLE_PROPAGATION_TIME` beside its only remaining uses in `governance.cpp` and document its current additional-relay role

  Review context: #7442 (review)

  ## How was this tested?

  - full headless build
  - `test_dash --run_test=governance_inv_tests,net_tests,ratecheck_tests,miner_tests`
  - `lint-whitespace.py`
  - `lint-include-guards.py`
  - `lint-includes.py`
  - `lint-circular-dependencies.py`
  - `git diff --check`

  The mandatory independent pre-PR code-review gate returned `ship` with no findings.

ACKs for top commit:
  UdjinM6:
    utACK 2673240

Tree-SHA512: 5e4ef12b85f355b130e90c305f53b5b58aef8708cb15f58f40afa2bcfdfac548a3784b8fc45a687df96de0b399cfa80137b75cde21aeaa213af03aff6e799b49

Author: PastaPastaPasta

src/governance/governance.cpp

@@ -32,7 +32,8 @@ namespace {
 constexpr std::chrono::seconds GOVERNANCE_DELETION_DELAY{10min};
 constexpr std::chrono::seconds GOVERNANCE_ORPHAN_EXPIRATION_TIME{10min};
 constexpr std::chrono::seconds MAX_TIME_FUTURE_DEVIATION{1h};
-using governance::RELIABLE_PROPAGATION_TIME;
+// Margin below MAX_TIME_FUTURE_DEVIATION so lagging-clock peers don't reject near-limit objects.
+constexpr std::chrono::seconds RELIABLE_PROPAGATION_TIME{60};
 
 bool IsSyncableObject(const std::shared_ptr<CGovernanceObject>& govobj)
 {

src/governance/governance.h

@@ -10,7 +10,6 @@
 #include <primitives/transaction.h>
 #include <sync.h>
 
-#include <chrono>
 #include <limits>
 #include <map>
 #include <memory>
@@ -39,8 +38,6 @@ class UniValue;
 
 namespace governance {
 class SuperblockManager;
-// How long a requested governance inv hash remains in the request cache.
-inline constexpr std::chrono::seconds RELIABLE_PROPAGATION_TIME{60};
 } // namespace governance
 
 using vote_time_pair_t = std::pair<CGovernanceVote, int64_t>;