dashbord: restrict freebsd-riscv64-unmatched to the same repos as linux-riscv64-unmatched

Fixes golang/go#56273.
Updates golang/go#53466.

Change-Id: I6e796006f8f7120ae05d5e62cdbc7cdd9d146f7e
Reviewed-on: https://go-review.googlesource.com/c/build/+/456575
Auto-Submit: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>

dashboard/builders.go

@@ -2881,6 +2881,13 @@ func init() {
 		distTestAdjust: riscvDistTestPolicy,
 		privateGoProxy: true, // this builder is behind firewall
 		SkipSnapshot:   true, // The builder has a slow uplink bandwidth.
+		buildsRepo: func(repo, branch, goBranch string) bool {
+			// see https://go.dev/issue/53745
+			if repo == "perf" {
+				return false
+			}
+			return onlyMasterDefault(repo, branch, goBranch)
+		},
 	})
 	addBuilder(BuildConfig{
 		Name:           "plan9-arm",