Extract shared RollbackQuietlyAsync helper into DapperRepository base class

Avoids duplicating the transaction-rollback-swallowing logic in every repository that needs it, starting with BreweryRepository.

web/backend/Features/Features.Breweries/Repository/BreweryRepository.cs

@@ -441,22 +441,6 @@ public class BreweryRepository(ISqlConnectionFactory connectionFactory)
         }
     }
 
-    /// <summary>
-    ///     Rolls back <paramref name="transaction" />, swallowing any exception the rollback itself
-    ///     raises (for example when the provider has already completed the transaction after a
-    ///     connection failure) so the exception that triggered the rollback is what propagates.
-    /// </summary>
-    private static async Task RollbackQuietlyAsync(DbTransaction transaction)
-    {
-        try
-        {
-            await transaction.RollbackAsync();
-        }
-        catch
-        {
-            // Ignore: the original exception (rethrown by the caller) is what matters here.
-        }
-    }
 
     /// <summary>
     ///     Composes a joined row's <see cref="BreweryPost" />, <see cref="BreweryPostLocation" />,