fix: simplify keepalive error message

Use simpler "Connection to Depot runner lost" message that focuses users
on the troubleshooting documentation.

Author: PedroGuerraPT

pkg/buildx/commands/build.go

@@ -1097,7 +1097,7 @@ func wrapBuildError(err error, bake bool) error {
 			return &wrapped{err, msg}
 		}
 		if st.Code() == codes.Unavailable && strings.Contains(st.Message(), "keepalive ping failed") {
-			msg := "Connection to BuildKit lost. This error occurs when BuildKit is shut down, often due to the runner reaching resource starvation caused by an Out of Memory (OOM) condition.\n\nFor troubleshooting steps, visit: https://depot.dev/docs/container-builds/troubleshooting#error-keep-alive-ping-failed-to-receive-ack-within-timeout"
+			msg := "Connection to Depot runner lost.\n\nFor troubleshooting steps, visit: https://depot.dev/docs/container-builds/troubleshooting#error-keep-alive-ping-failed-to-receive-ack-within-timeout"
 			return &wrapped{err, msg}
 		}
 	}
@@ -1178,7 +1178,7 @@ func rewriteFriendlyErrors(err error) error {
 		return errors.New("build canceled")
 	}
 	if strings.Contains(err.Error(), "keepalive ping failed") {
-		return errors.New("Connection to BuildKit lost. This error occurs when BuildKit is shut down, often due to the runner reaching resource starvation caused by an Out of Memory (OOM) condition.\n\nFor troubleshooting steps, visit: https://depot.dev/docs/container-builds/troubleshooting#error-keep-alive-ping-failed-to-receive-ack-within-timeout")
+		return errors.New("Connection to Depot runner lost.\n\nFor troubleshooting steps, visit: https://depot.dev/docs/container-builds/troubleshooting#error-keep-alive-ping-failed-to-receive-ack-within-timeout")
 	}
 	return err
 }