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/Server.Tests/Tests/Buffers/ValueStringBuilderTests.cs

@@ -52,19 +52,6 @@ public class ValueStringBuilderTests
     // writes into the shared buffer, and Append() reconciles via `this = handler._builder`.
     // Critical to detect if C# compiler codegen changes break this assumption.
 
-    [Fact]
-    public void Interpolation_Stackalloc_NoGrow()
-    {
-        // Stackalloc buffer large enough — no Grow needed.
-        // Validates: copy's Span shares same stackalloc memory, _length is reconciled.
-        var sb = new ValueStringBuilder(stackalloc char[64]);
-        sb.Append($"Hello {42} world");
-
-        Assert.Equal("Hello 42 world", sb.ToString());
-        Assert.Equal(14, sb.Length);
-        sb.Dispose();
-    }
-
     [Fact]
     public void Interpolation_Stackalloc_WithGrow()
     {
@@ -82,20 +69,6 @@ public class ValueStringBuilderTests
         sb.Dispose();
     }
 
-    [Fact]
-    public void Interpolation_Stackalloc_PreExistingContent_NoGrow()
-    {
-        // Append plain text first, then interpolation. Buffer large enough.
-        // Validates: interpolation appends after existing content, doesn't overwrite.
-        var sb = new ValueStringBuilder(stackalloc char[64]);
-        sb.Append("prefix-");
-        sb.Append($"value={99}");
-
-        Assert.Equal("prefix-value=99", sb.ToString());
-        Assert.Equal(15, sb.Length);
-        sb.Dispose();
-    }
-
     [Fact]
     public void Interpolation_Stackalloc_PreExistingContent_WithGrow()
     {
@@ -264,20 +237,6 @@ public class ValueStringBuilderTests
         sb.Dispose();
     }
 
-    [Fact]
-    public void Interpolation_Stackalloc_DisposeAfterGrow()
-    {
-        // After Grow moves stackalloc to pool, Dispose should return the pooled array.
-        // Validates: _arrayToReturnToPool is correctly reconciled so Dispose works.
-        var sb = new ValueStringBuilder(stackalloc char[4]);
-        sb.Append($"grow beyond stackalloc: {12345}");
-        // If _arrayToReturnToPool wasn't reconciled, Dispose would either
-        // not return the pooled array (leak) or return null (no-op when it shouldn't be).
-        sb.Dispose();
-        // No assertion needed — if _arrayToReturnToPool was wrong, pool corruption
-        // would surface as test failures elsewhere. The test passing = no crash.
-    }
-
     [Fact]
     public void Interpolation_Heap_DoubleGrow()
     {