🔥 e2e mock: simplify the Crowdsec LAPI mock

Per review, trim the mock to the minimum the plugin actually exercises:

- Drop the stream delta bookkeeping (startup flag + "already streamed" set).
  The plugin re-Sets/Deletes its cache on every poll, so reporting the whole
  active set as "new" and removed ones as "deleted" is enough.
- Shrink the Decision struct to the three fields the plugin reads
  (value/type/duration); drop id/origin/scope/scenario and the id counter.
- Drop API-key auth and the /admin/reset endpoint — no scenario exercises
  either. Also drop the now-unused lapi_reset helper.
- Replace the store struct + methods with two package-level maps + a mutex.

mocklapi/main.go: 234 -> 118 lines. All six scenarios still pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/e2e/mock/lib/common.sh

@@ -143,10 +143,6 @@ lapi_delete_decision() {
   curl -sS -X DELETE "http://127.0.0.1:${LAPI_PORT}/admin/decisions?ip=${ip}" >/dev/null
 }
 
-lapi_reset() {
-  curl -sS -X POST "http://127.0.0.1:${LAPI_PORT}/admin/reset" >/dev/null
-}
-
 # --- stack lifecycle ---------------------------------------------------------
 
 # start_stack SCENARIO_DIR
@@ -174,8 +170,7 @@ start_stack() {
 
   "$mock_bin" \
     --lapi-addr "127.0.0.1:${LAPI_PORT}" \
-    --backend-addr "127.0.0.1:${BACKEND_PORT}" \
-    --api-key "${LAPI_KEY}" >"$WORKDIR/mock.log" 2>&1 &
+    --backend-addr "127.0.0.1:${BACKEND_PORT}" >"$WORKDIR/mock.log" 2>&1 &
   MOCK_PID=$!
 
   ( cd "$WORKDIR" && exec "$traefik_bin" --configfile=traefik.yml ) >"$WORKDIR/traefik.log" 2>&1 &