Make restart behavior of ustreamer systemd service more resilient (#1891)

Resolves tiny-pilot/tinypilot-pro#1487

This change introduces new restart behavior in `ustreamer.service` to
allow ustreamer to start more consistently.

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Author: db39

debian-pkg/debian/tinypilot.ustreamer.service

@@ -1,13 +1,20 @@
 [Unit]
 Description=uStreamer - Lightweight, optimized video encoder
 After=syslog.target network.target
+# Give up if we restart on failure 20 times within 5 minutes (300 seconds).
+StartLimitIntervalSec=300
+StartLimitBurst=20
 
 [Service]
 Type=simple
 User=ustreamer
 WorkingDirectory=/opt/ustreamer-launcher
 ExecStart=/opt/ustreamer-launcher/launch
 Restart=always
+# ustreamer sometimes fails to start. Introducing extra restart time and
+# start limits works around this problem. More details and investigation in this
+# issue: https://github.com/tiny-pilot/tinypilot-pro/issues/1487
+RestartSec=2
 
 [Install]
 WantedBy=multi-user.target