test: remove trivial, duplicate and content-value tests (#2721)

## Summary
Many tests proved a specific change when it landed but don't need to run on every CI build forever. This removes **202 test methods and 9 files: 313 test cases, 2,247 → 1,934**. UOContent.Tests drops from about 14s to about 5s locally.

Removed:
- **Tautologies.** Asserting a constant, a constructor readback or a trivial getter, or testing BCL behavior.
- **Exact duplicates** of a surviving test on the same code path.
- **Obsolete regressions** whose failure can no longer be expressed.
- **Game-content values** shard owners customize (era drop rates, loot and skill tables, single-creature tuning). Each customization would otherwise force a test fix.

## How it was decided
1. Every test was classified, with a reason, by a per-shard sweep over all 287 test files.
2. Each proposed deletion was then checked by a second, adversarial reviewer against the surviving tests and the production code.
3. Anything that was the only coverage of a separate code path was **kept**, even where it looked like a duplicate. Examples: the unsigned `SpanReader`/`SpanWriter` methods, the at-location versus bounds enumerators, null-map enumerables, the security filters, archive-journal state transitions. About 130 proposed deletions were rejected this way.

Whole files removed:
- `FishingTests`, apart from 3 tests: the map-edge scan, serpent cleanup, and SOS chest consumption. The SOS test now stops at the first chest instead of measuring a catch rate. The multi-million-cast rate simulations are gone.
- `LordOaksTests` and `MeerEnragedTests` (single-creature tests).
- `AutoArchiveHelperTests`, `JsonDiscoverableTypeAttributeTests`, `DecimalSerializationTests` and `EnumConversionTests` (tautologies, or tests of their own local helpers).
- `NetworkStatsTests`.
- `MigratedDataLoadTests` (a subset of `AllSpawnFilesLoadTests`).
- `SpawnerFixtureCapture`: a capture tool, not a test, and its `version == 12` assert can no longer pass. The `.bin` fixtures it produced stay.

## Tests
- Server.Tests: 811 pass.
- UOContent.Tests: 1,123 pass.

A follow-up PR, stacked on this one, fixes how the remaining tests behave: shared state, CI-vacuous tests, harness duplication.

Projects/UOContent.Tests/Tests/Engines/Pathing/Multi/MultiEdgeCaseTests.cs

@@ -130,33 +130,4 @@ public class MultiEdgeCaseTests
             }
         }
     }
-
-    /// <summary>
-    /// Extensible slot for repo-owner-supplied gnarly placements. The assertion already covers
-    /// any (map,x,y) by construction — only the coordinates need filling in.
-    ///
-    /// TODO(coords): repo owner to supply (map,x,y) for a static tree inside a footprint and a
-    /// dungeon cave-wall corner; add InlineData rows here — the assertion already covers them by
-    /// construction. (Left intentionally unhunted: do not invent tree/dungeon coords.)
-    /// </summary>
-    [SkippableTheory]
-    [InlineData(MapId, HouseX, HouseY)] // known-good open Trammel placement (passes today)
-    public void UserSuppliedScenarios_SynthesizerMatchesCheckMovement(int mapId, int x, int y)
-    {
-        TileDataRequirement.SkipIfMissing();
-        StepCache.Instance.Clear();
-        var map = Map.Maps[mapId];
-
-        var multi = new TestMulti(GuildHouseId);
-        map.GetAverageZ(x, y, out _, out var z, out _);
-        multi.MoveToWorld(new Point3D(x, y, (sbyte)z), map);
-        try
-        {
-            MultiTestSupport.AssertSynthesizerMatchesCheckMovement(multi, map);
-        }
-        finally
-        {
-            multi.Delete();
-        }
-    }
 }