fix unpaired deref when write_file fails due to nametoolong (#23438)

Fixes test\regression\issue\23316-long-path-spawn.test.ts

The problem was ``await Bun.write(join(deepPath, "test.js"),
`console.log("hello");`);`` was failing because the name was too long,
but it failed before refConcurrently was called and it called
unrefConcurrently after failing. so then when the subprocess spawned it
didn't ref.

---------

Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>

src/bun.js/webcore/blob/write_file.zig

@@ -350,6 +350,7 @@ pub const WriteFileWindows = struct {
     err: ?bun.sys.Error = null,
     total_written: usize = 0,
     event_loop: *jsc.EventLoop,
+    poll_ref: bun.Async.KeepAlive = .{},
 
     owned_fd: bool = false,
 
@@ -404,7 +405,7 @@ pub const WriteFileWindows = struct {
             },
         }
 
-        write_file.event_loop.refConcurrently();
+        write_file.poll_ref.ref(write_file.event_loop.virtual_machine);
         return write_file;
     }
 
@@ -481,7 +482,6 @@ pub const WriteFileWindows = struct {
     fn mkdirp(this: *WriteFileWindows) void {
         log("mkdirp", .{});
         this.mkdirp_if_not_exists = false;
-        this.event_loop.refConcurrently();
 
         const path = this.file_blob.store.?.data.file.pathlike.path.slice();
         jsc.Node.fs.Async.AsyncMkdirp.new(.{
@@ -494,8 +494,6 @@ pub const WriteFileWindows = struct {
     }
 
     fn onMkdirpComplete(this: *WriteFileWindows) void {
-        this.event_loop.unrefConcurrently();
-
         const err = this.err;
         this.err = null;
         if (err) |err_| {
@@ -539,7 +537,6 @@ pub const WriteFileWindows = struct {
     }
 
     pub fn onFinish(container: *WriteFileWindows) WriteFileWindowsError {
-        container.event_loop.unrefConcurrently();
         var event_loop = container.event_loop;
         event_loop.enter();
         defer event_loop.exit();
@@ -623,6 +620,7 @@ pub const WriteFileWindows = struct {
         }
         this.file_blob.store.?.deref();
         this.bytes_blob.store.?.deref();
+        this.poll_ref.disable();
         uv.uv_fs_req_cleanup(&this.io_request);
         bun.destroy(this);
     }

test/regression/issue/23316-long-path-spawn.test.ts

@@ -89,7 +89,8 @@ test("spawn should handle cwd paths with disabled 8.3 names on Windows", async (
       stdout: "inherit",
       stderr: "inherit",
     });
-    await proc.exited;
+    const exitCode = await proc.exited;
+    if (exitCode !== 0) throw new Error("process exited");
   } catch (e) {
     err = e;
   }