Merge #6964: perf: remove duplicated check of same key in the instant send database

42b3341 perf: remove duplicated check of same key in the instant send database (Konstantin Akimov)

Pull request description:

  ## Issue being fixed or feature implemented

  Previous implementation checked both Deterministic and Non-deterministic instant send locks; though once non-determinstic has been removed, implementation has been updated and now the same key is checked twice.

  ## What was done?
  This PR removes duplicated check

  ## How Has This Been Tested?
  See CI

  ## Breaking Changes
  N/A

  ## Checklist:
  - [x] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone

ACKs for top commit:
  PastaPastaPasta:
    utACK [42b3341](42b3341)
  kwvg:
    utACK 42b3341
  UdjinM6:
    utACK 42b3341

Tree-SHA512: f0213e7ad8f4d380561538d194a9fc9ed1b1ed4580f1848aa14d7958b817ac716e09bb4b83f611a86b2f1b8d920fb65f87721b35bee8f7e84b97193eae459adb

Author: PastaPastaPasta

src/instantsend/db.cpp

@@ -280,11 +280,7 @@ InstantSendLockPtr CInstantSendDb::GetInstantSendLockByHashInternal(const uint25
     ret = std::make_shared<InstantSendLock>();
     bool exists = db->Read(std::make_tuple(DB_ISLOCK_BY_HASH, hash), *ret);
     if (!exists || (::SerializeHash(*ret) != hash)) {
-        ret = std::make_shared<InstantSendLock>();
-        exists = db->Read(std::make_tuple(DB_ISLOCK_BY_HASH, hash), *ret);
-        if (!exists || (::SerializeHash(*ret) != hash)) {
-            ret = nullptr;
-        }
+        ret = nullptr;
     }
     islockCache.insert(hash, ret);
     return ret;