buildkite: increase timeout for population latency tests

We are seeing the execution time exceed the default 60 minutes Buidlkite
timeout sometimes.

Signed-off-by: Nikita Kalyazin <kalyazin@amazon.com>

Author: kalyazin

.buildkite/pipeline_perf.py

@@ -49,6 +49,7 @@
         "label": "population-latency",
         "tests": "integration_tests/performance/test_snapshot.py::test_population_latency",
         "devtool_opts": "-c 1-12 -m 0",
+        "timeout_in_minutes": 90,
     },
     "vsock-throughput": {
         "label": "vsock-throughput",