dashboard: update host-linux-loong64-3a5000 owner

XiaodongLoong has left Loongson and is no longer a member of the Loongson
Go team. Thanks again for his contribution to the porting and maintenance
of loong64 in Go.

Change-Id: I2206233a73c88bb4d693c417e5aea173caa354fe
Reviewed-on: https://go-review.googlesource.com/c/build/+/585296
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Run-TryBot: abner chenc <[email protected]>

Author: abner-chenc

dashboard/builders.go

@@ -371,7 +371,7 @@ var Hosts = map[string]*HostConfig{
 	},
 	"host-linux-loong64-3a5000": {
 		Notes:       "Loongson 3A5000 Box hosted by Loongson; loong64 is the short name of LoongArch 64 bit version",
-		Owners:      []*gophers.Person{gh("XiaodongLoong"), gh("abner-chenc")},
+		Owners:      []*gophers.Person{gh("abner-chenc")},
 		IsReverse:   true,
 		ExpectNum:   5,
 		GoBootstrap: "none",