test(e2e): transparent whitelist bypass + sniffing (gost#899)

Reproduce the regression where a domain-only whitelist bypass on a red
(transparent) proxy rejected every connection: the pre-sniffing bypass
check ran against the bare destination IP, which is never in a domain
whitelist, before SNI sniffing could match. A privileged container
redirects outbound TCP to the red service; asserts an allowlisted SNI
is forwarded (hello-gost) and a non-allowlisted SNI is rejected.

tests/e2e/testdata/red_sniffing/whitelist.yaml

@@ -0,0 +1,27 @@
+# gost#899: whitelist bypass + sniffing on a transparent (red) proxy.
+# The whitelist contains only a domain ("https-echo", the docker network alias
+# of the HTTPS echo container). A bare destination IP is never in it, so on a
+# broken build the pre-sniffing IP bypass check rejects every connection
+# before SNI sniffing can match the host. The fix skips that check in
+# whitelist mode and lets the sniffer drive the decision from the SNI.
+log:
+  level: debug
+services:
+  - name: transparent-egress
+    addr: ":12345"
+    bypass: allowlist
+    metadata:
+      so_mark: 114514
+    handler:
+      type: red
+      metadata:
+        sniffing: true
+        sniffing.timeout: 5s
+        sniffing.fallback: true
+    listener:
+      type: red
+bypasses:
+  - name: allowlist
+    whitelist: true
+    matchers:
+      - https-echo