Revert "Treat blocks with "return" as "noreturn""

This reverts commit 135b91aecd9be1f6f5806b667e07e383dd481198.

"endsWithBreak()" is not a meaningful question to ask and should not be
used this way. A simple example that defeats this logic is:

```zig
export fn entry() void {
    outer: {
        {
            break :outer;
        }
        return;
    }
}
```

1 files changed, 0 insertions, 14 deletions

diff --git a/test/cases/compile_errors/stage2/code_after_return_in_block_is_unreachable.zig b/test/cases/compile_errors/stage2/code_after_return_in_block_is_unreachable.zig
deleted file mode 100644
index e62edcb358..0000000000
--- a/test/cases/compile_errors/stage2/code_after_return_in_block_is_unreachable.zig
+++ /dev/null
@@ -1,14 +0,0 @@
-export fn entry() void {
-    {
-        return;
-    }
-
-    return;
-}
-
-// error
-// target=native
-//
-// :6:5: error: unreachable code
-// :2:5: note: control flow is diverted here
-