Merge #6273: backport: merge bitcoin#27015 (resolve flaky addrman uni…

…t test)

925870d merge bitcoin#27015: bitcoin#26847 fixups (AddrMan totals) (Kittywhiskers Van Gogh)

Pull request description:

  ## Additional Information

  As part of [dash#6254](#6254), [bitcoin#26847](bitcoin#26847) was backported and since then, it was observed that unit tests were flakier than expected ([build](https://gitlab.com/dashpay/dash/-/jobs/7811041841), [build](https://gitlab.com/dashpay/dash/-/jobs/7802460298)).

  The flakiness was caused by behavior introduced by the aforementioned backport, this was resolved upstream with [bitcoin#27015](bitcoin#27015), which this pull request contains.

  ## Breaking Changes

  None observed.

  ## Checklist:

  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas **(note: N/A)**
  - [x] I have added or updated relevant unit/integration/functional/e2e tests
  - [x] I have made corresponding changes to the documentation **(note: N/A)**
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  UdjinM6:
    utACK 925870d
  knst:
    ACK 925870d

Tree-SHA512: 20fc8fb1b162803a71ec4087685460f52ed56c3c86d46ecac4cc0ef59c95b4b6206f0c53bef256242a4a5babb76e3564cfba56a84cbe844e187035de2308b818

src/addrman.h

@@ -117,7 +117,7 @@ class AddrMan
     * @param[in] in_new           Select addresses only from one table (true = new, false = tried, nullopt = both)
     * @return                     Number of unique addresses that match specified options.
     */
-    size_t Size(std::optional<Network> net = {}, std::optional<bool> in_new = {}) const;
+    size_t Size(std::optional<Network> net = std::nullopt, std::optional<bool> in_new = std::nullopt) const;
 
     /**
      * Attempt to add one or more addresses to addrman's new table.

src/test/addrman_tests.cpp

@@ -1035,8 +1035,6 @@ BOOST_AUTO_TEST_CASE(load_addrman_corrupted)
     } catch (const std::exception&) {
         exceptionThrown = true;
     }
-    // Even though de-serialization failed addrman is not left in a clean state.
-    BOOST_CHECK(addrman1.Size() == 1);
     BOOST_CHECK(exceptionThrown);
 
     // Test that ReadFromStream fails if peers.dat is corrupt