dashboard: drop known issue from linux-loong64-3a5000

The loong64 port is now complete with tests passing.

For golang/go#46229.

Change-Id: Ie0c0aaf461c7ef019125716b35594da12b0a7492
Reviewed-on: https://go-review.googlesource.com/c/build/+/407506
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
diff --git a/dashboard/builders.go b/dashboard/builders.go
index 567dd85..9fa8fd5 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -2551,7 +2551,6 @@
 			"GOARCH=loong64",
 			"GOHOSTARCH=loong64",
 		},
-		KnownIssue: 46229,
 	})
 	addBuilder(BuildConfig{
 		FlakyNet:       true,