Reenable muted test (#91366)
I can't reproduce the failure. The failure looks like we it isn't
including the "_as_string" value:
```
{
"stash" : {
"body" : {
"took" : 4,
"timed_out" : false,
"_shards" : {
"total" : 2,
"successful" : 2,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 1,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : [
{
"_index" : "date_test_2",
"_id" : "5",
"_score" : 1.0,
"_source" : {
"date_field" : "2021-05-01T00:00:00.000Z"
}
}
]
},
"aggregations" : {
"date_field_max" : {
"value" : 1.6198272E12
}
}
}
}
}
```
Which could be because the "unmapped" max was the "lead" aggregation. It
shouldn't and we've tried to make sure it doesn't, but maybe that's what
happened?
Either way I can't reproduce and don't see similar failures.
Nik Everett