dashboard: clear known issue for iOS builder

The work needed to resolve go.dev/issue/49616 looks
to be complete, and the builder is passing reliably.

Updates golang/go#49616.

Change-Id: I90253c7751f97f081496abe90b1e827992afaf6e
Reviewed-on: https://go-review.googlesource.com/c/build/+/369255
Trust: Dmitri Shuralyov <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: dmitshur

dashboard/builders.go

@@ -2499,7 +2499,6 @@ func init() {
 		buildsRepo: func(repo, branch, goBranch string) bool {
 			return repo == "go" && branch == "master" && goBranch == "master"
 		},
-		KnownIssue: 49616,
 	})
 	addBuilder(BuildConfig{
 		Name:     "android-arm64-corellium",