Elasticsuite Tracker does not properly support ampersand in categories title (and probably in product names, cms pages title, etc)

[rbayet]

Preconditions

Magento Version : EE 2.2.2

ElasticSuite Version : 2.5.0

Environment : Developer mode

Third party modules : lots, none related to search

Steps to reproduce

1. Name a category with an ampersand (&) in the title, for instance "Baby & Child"
2. Place a product in that category
3. Navigate in frontend on the home page, the "Baby & Child" category, the product page, perform a search to find that product

Expected result

1. After the cron:run reindexing of tracker events, events document should be present in the Elasticsearch index with the correct page title (category page event), category label (product page event)

Actual result

1. The ampersand generates additional request parameters/variables
2. The original parameters/variables contain partial value and those extra parameters are pushed "as is" as empty ES document fields
3. Those bogus document fields become part of the mapping

[afoucret]

Fixed by PR #773