caddy-frontend: Try backend only once from ATS

ATS by default tries 4 times (1 non configurable, 3 retries) a given query to
the backend. Despite of "connection" in the name, ATS waits for first byte
from the backend, and it means that backend might already processing the
request, just no bytes are sent. In order to avoid this allow ATS to try only
once.

software/caddy-frontend/buildout.hash.cfg

@@ -74,7 +74,7 @@ md5sum = 8cde04bfd0c0e9bd56744b988275cfd8
 
 [template-trafficserver-records-config]
 filename = templates/trafficserver/records.config.jinja2
-md5sum = 5ef0ebc37437ada7cc176e663da5f36c
+md5sum = f5819637cdda0ed68af8806b83ecdd3c
 
 [template-trafficserver-storage-config]
 filename = templates/trafficserver/storage.config.jinja2

software/caddy-frontend/templates/trafficserver/records.config.jinja2

@@ -79,8 +79,10 @@ CONFIG proxy.config.net.default_inactivity_timeout INT 86400
 # Origin server connect attempts. Docs:
 #    https://docs.trafficserver.apache.org/records.config#origin-server-connect-attempts
 ##############################################################################
-CONFIG proxy.config.http.connect_attempts_max_retries INT 3
-CONFIG proxy.config.http.connect_attempts_max_retries_dead_server INT 1
+# Try only once to connect (do not retry)
+CONFIG proxy.config.http.connect_attempts_max_retries INT 0
+# Try only once with server marked dead (do not retry)
+CONFIG proxy.config.http.connect_attempts_max_retries_dead_server INT 0
 CONFIG proxy.config.http.connect_attempts_rr_retries INT 3
 CONFIG proxy.config.http.connect_attempts_timeout INT 30
 CONFIG proxy.config.http.post_connect_attempts_timeout INT 1800