REGTESTS: extend the default I/O timeouts and make them overridable

With the CI occasionally slowing down, we're starting to see again some
spurious failures despite the long 1-second timeouts. This reports false
positives that are disturbing and doesn't provide as much value as this
could. However at this delay it already becomes a pain for developers
to wait for the tests to complete.

This commit adds support for the new environment variable
HAPROXY_TEST_TIMEOUT that will allow anyone to modify the connect,
client and server timeouts. It was set to 5 seconds by default, which
should be plenty for quite some time in the CI. All relevant values
that were 200ms or above were replaced by this one. A few larger
values were left as they are special. One test for the set-timeout
action that used to rely on a fixed 1-sec value was extended to a
fixed 5-sec, as the timeout is normally not reached, but it needs
to be known to compare the old and new values.
diff --git a/reg-tests/connection/cli_src_dst.vtc b/reg-tests/connection/cli_src_dst.vtc
index fa12bc8..6809d39 100644
--- a/reg-tests/connection/cli_src_dst.vtc
+++ b/reg-tests/connection/cli_src_dst.vtc
@@ -6,9 +6,9 @@
 haproxy h1 -conf {
     defaults
         mode http
-        timeout connect 1s
-        timeout client  1s
-        timeout server  1s
+        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout server  "${HAPROXY_TEST_TIMEOUT-5s}"
 
     frontend fe1
         bind "fd@${fe1}"
diff --git a/reg-tests/connection/dispatch.vtc b/reg-tests/connection/dispatch.vtc
index fccd6ec..8696b50 100644
--- a/reg-tests/connection/dispatch.vtc
+++ b/reg-tests/connection/dispatch.vtc
@@ -14,9 +14,9 @@
 haproxy h1 -conf {
 defaults
     log global
-    timeout connect 1s
-    timeout client 1s
-    timeout server 1s
+    timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+    timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
+    timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
 
 listen fe_tcp
     bind "fd@${fe_tcp}"
diff --git a/reg-tests/connection/proxy_protocol_random_fail.vtc b/reg-tests/connection/proxy_protocol_random_fail.vtc
index 8884daa..bcaa03c 100644
--- a/reg-tests/connection/proxy_protocol_random_fail.vtc
+++ b/reg-tests/connection/proxy_protocol_random_fail.vtc
@@ -30,9 +30,9 @@
 
     defaults
         mode http
-        timeout client 1s
-        timeout server 1s
-        timeout connect 1s
+        timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
         log global
 
     listen http
diff --git a/reg-tests/connection/proxy_protocol_tlv_validation.vtc b/reg-tests/connection/proxy_protocol_tlv_validation.vtc
index 284bc91..8c7d734 100644
--- a/reg-tests/connection/proxy_protocol_tlv_validation.vtc
+++ b/reg-tests/connection/proxy_protocol_tlv_validation.vtc
@@ -10,9 +10,9 @@
 haproxy h1 -conf {
     defaults
         mode http
-        timeout connect 1s
-        timeout client  1s
-        timeout server  1s
+        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout server  "${HAPROXY_TEST_TIMEOUT-5s}"
 
     frontend a
         bind "fd@${fe1}" accept-proxy
@@ -43,9 +43,9 @@
 haproxy h2 -conf {
     defaults
         mode http
-        timeout connect 1s
-        timeout client  1s
-        timeout server  1s
+        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout server  "${HAPROXY_TEST_TIMEOUT-5s}"
 
     frontend a
         bind "fd@${fe1}" accept-proxy
@@ -80,9 +80,9 @@
 haproxy h3 -conf {
     defaults
         mode http
-        timeout connect 1s
-        timeout client  1s
-        timeout server  1s
+        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout server  "${HAPROXY_TEST_TIMEOUT-5s}"
 
     frontend a
         bind "fd@${fe1}" accept-proxy
@@ -112,9 +112,9 @@
 haproxy h4 -conf {
     defaults
         mode http
-        timeout connect 1s
-        timeout client  1s
-        timeout server  1s
+        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout server  "${HAPROXY_TEST_TIMEOUT-5s}"
 
     frontend a
         bind "fd@${fe1}" accept-proxy