ci: add regression test for boot race condition

If two instances start up at the same time, they end up with different
keys on both ends. Test this with different delays of 2 (working), 1
(flaky) and 0 (broken) seconds.

Signed-off-by: Paul Spooren <mail@aparcar.org>

.ci/boot_race/b.toml

@@ -0,0 +1,14 @@
+public_key = "rp-b-public-key"
+secret_key = "rp-b-secret-key"
+listen = ["127.0.0.1:9998"]
+verbosity = "Verbose"
+
+[api]
+listen_path = []
+listen_fd = []
+stream_fd = []
+
+[[peers]]
+public_key = "rp-a-public-key"
+endpoint = "127.0.0.1:9999"
+key_out = "rp-a-key-out.txt"