Address second round of Jesper Schulz-Wedde's review on PR #159

- commit-shared-test-fixture-inside-lazy-initialize.md: fundamentally
  rewritten. AutoCommit is the documented default TransactionModel, not
  AutoRollback. Explains the real mechanism (Commit() protects a fixture
  from the test method's own later deliberate rollback, per Codeunit.Run/
  TransactionModel-property semantics) and the TestIsolation dependency
  (Disabled/Codeunit survive across methods, Function does not). Fixtures
  rewritten to demonstrate the actual failure/success shape.
- transactionmodel-attribute-governs-test-transactions.md: now states the
  AutoCommit default explicitly and agrees with the article above, closing
  the contradiction Jesper flagged between the two testing articles.
- Deleted confirm-needs-strsubstno-before-confirmhandler-sees-substituted-text
  (.md/.good.al/.bad.al): the underlying platform bug (microsoft/
  ALAppExtensions#23935) was closed as completed in Feb 2024; cannot be
  reproduced or bc-version-pinned on any currently supported version.
- table-relation-test-exclude-known-invalid-relations-via-event.md: added
  the [Scope('OnPrem')] boundary verified against BCApps' Table Relation
  Test codeunit.
- use-assert-isfalse-not-asserterror-for-boolean-checks.md: added a Scope
  section resolving the overlap with asserterror-needs-expectederror-and-code.
- al-testing-review.md: fixed the shared-fixture cue to catch the actual
  anti-pattern instead of the compliant shape, added the missing cue for
  use-assert-isfalse-not-asserterror-for-boolean-checks, wired precedence
  between it and the generic asserterror rule, and removed the cue for the
  deleted article.
- Added in-file Source provenance (specific fluxxus.nl post per article,
  with what was independently verified vs. taken from the post) to the
  three surviving externally-inspired articles, per Jesper's request that
  provenance live in the knowledge file itself, not only the PR description.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

microsoft/knowledge/testing/commit-shared-test-fixture-inside-lazy-initialize.good.al

@@ -1,9 +1,12 @@
 codeunit 50142 "Sample Test Library"
 {
+    Subtype = Test;
+
     var
         Initialized: Boolean;
+        RollBackMsg: Label 'Revert back the tables to their original state.';
 
-    procedure Initialize()
+    local procedure Initialize()
     begin
         if Initialized then
             exit;
@@ -17,4 +20,14 @@ codeunit 50142 "Sample Test Library"
     begin
         // insert master/setup data shared across every test in this codeunit
     end;
+
+    [Test]
+    procedure FirstTestUsesSharedFixture()
+    begin
+        Initialize();
+
+        // exercise/verify against the shared fixture, then make scratch changes of its own
+
+        asserterror Error(RollBackMsg);
+    end;
 }