InitIndex: Allow to configure index.maxLimit for Elasticsearch

When using the Elasticsearch secondary index, `index.maxLimit` should
not exceed the value of `index.max_result_window` configured on the
Elasticsearch server.

By default `index.maxLimit` is not set, which effectively means that the
value used is Integer.MAX_VALUE. When Elasticsearch is used out of the
box the default `index.max_result_window` is 10000, and this results in
query failures:

  "Result window is too large, from + size must be less than or equal
   to: [10000] but was [2147483647]."

When the index type is Elasticsearch, prompt for the max limit during
initialization, defaulting to Elasticsearch's default value of 10000.

Bug: Issue 8527
Change-Id: I983a83b5cdd0eaf5ba875c3310dfd484e53fe064

Documentation/config-gerrit.txt

@@ -2689,9 +2689,10 @@ result lists). Set to 0 for no limit.
 +
 When `index.type` is set to `ELASTICSEARCH`, this value should not exceed
 the `index.max_result_window` value configured on the Elasticsearch
-server.
+server. If a value is not configured during site initialization, defaults to
+10000, which is the default value of `index.max_result_window` in Elasticsearch.
 +
-Defaults to no limit.
+When `index.type` is set to `LUCENE`, defaults to no limit.
 
 [[index.maxPages]]index.maxPages::
 +

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/InitIndex.java

@@ -70,6 +70,7 @@ class InitIndex implements InitStep {
           "Transport protocol", "protocol", "http", Sets.newHashSet("http", "https"));
       defaultServer.string("Hostname", "hostname", "localhost");
       defaultServer.string("Port", "port", "9200");
+      index.string("Result window size", "maxLimit", "10000");
     }
 
     if ((site.isNew || isEmptySite()) && type == IndexType.LUCENE) {