[CI] MultiMatchQueryBuilderTests#testToQuery fails

[danielmitterdorfer]

Note: There is an already closed issue for the same test (#36598) but as this one fails for a different reason I'm raising a new issue instead

• Test failure link: https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+6.8+periodic/28/console
• Test failure output:

   > Throwable #1: java.lang.AssertionError: query was marked as not cacheable in the context but this test indicates it should be cacheable: {
   >   "multi_match" : {
   >     "query" : "NOwGPnuTXe",
   >     "fields" : [ ],
   >     "type" : "best_fields",
   >     "operator" : "AND",
   >     "analyzer" : "standard",
   >     "slop" : 0,
   >     "prefix_length" : 0,
   >     "max_expansions" : 5,
   >     "lenient" : true,
   >     "cutoff_frequency" : 0.24390244,
   >     "zero_terms_query" : "NONE",
   >     "auto_generate_synonyms_phrase_query" : true,
   >     "fuzzy_transpositions" : true,
   >     "boost" : 0.1
   >   }
   > }

• Reproduction line:

./gradlew :server:unitTest \
  -Dtests.seed=D5624C9FE68BCB38 \
  -Dtests.class=org.elasticsearch.index.query.MultiMatchQueryBuilderTests \
  -Dtests.method="testToQuery" \
  -Dtests.security.manager=true \
  -Dtests.locale=ms \
  -Dtests.timezone=Asia/Tehran \
  -Dcompiler.java=12 \
  -Druntime.java=8

This reproduction line reliably reproduces locally as well.