Lower target-throughput for geonames term and phrase queries (#134)

From observation in the nightly environment we can see that occasionally
the phrase and term query may take >300ms and >1000ms. This leads to
unnecessary spikes in the latency charts.

Relates to elastic/elasticsearch#61957

geonames/challenges/default.json

@@ -77,13 +77,13 @@
  "operation": "term",
  "warmup-iterations": 500,
  "iterations": 1000,
- "target-throughput": 150
+ "target-throughput": 140
  },
  {
  "operation": "phrase",
  "warmup-iterations": 500,
  "iterations": 1000,
- "target-throughput": 150
+ "target-throughput": 140
  },
  {
  "operation": "country_agg_uncached",