CI Failure in kafka_server_rpfixture.fetch_leader_epoch

[travisdowns]

This is in a PR, which only changed python DT code, so it couldn't be the cause of this failure (so I'm assume it's a flake):

https://buildkite.com/redpanda/redpanda/builds/47976#018eedeb-71b6-445d-bd66-0d7f1d4bba6c

I couldn't quickly pull out the actual failing assertion.

JIRA Link: CORE-2428

[bharathv]

/var/lib/buildkite-agent/builds/buildkite-amd64-builders-i-02971863fd9d6bf64-1/redpanda/redpanda/src/v/redpanda/tests/fixture.h(515): fatal error: in "fetch_leader_epoch": Timed out at /var/lib/buildkite-agent/builds/buildkite-amd64-builders-i-02971863fd9d6bf64-1/redpanda/redpanda/src/v/redpanda/tests/fixture.h:515

Failure is in test fetch_leader_epoch , updating the title.

[bharathv]

INFO  2024-04-17 22:54:55,304 [shard 0:main] raft - [group_id:1, {kafka/foo/0}] consensus.cc:214 - [external_stepdown - trigger epoch change] Stepping down as leader in term 1, dirty offset 113^M
....
TRACE 2024-04-17 22:54:58,127 [shard 0:main] kvstore - kvstore.cc:212 - Apply op: update: key={bytes:10} value={{bytes=8, fragments=1}}^M
/var/lib/buildkite-agent/builds/buildkite-amd64-builders-i-02971863fd9d6bf64-1/redpanda/redpanda/src/v/redpanda/tests/fixture.h(515): fatal error: in "fetch_leader_epoch": Timed out at /var/lib/buildkite-agent/builds/buildkite-amd64-builders-i-02971863fd9d6bf64-1/redpanda/redpanda/src/v/redpanda/tests/fixture.h:515^M
...

The vote timer didn't fire on time (1.5s + jitter ..  <= 2.25s), perhaps something to do with debug build being slow. the wait time is 3s.. guess an obvious fix to bump the timeout but we could probably do something more deterministic.