[DOCS] Poor formatting of env. variables in EAP doc

The variable names in table in 4.5.1.2. Datasource Configuration Environment Variables are poorly formatted. There is no such variable name as:

POOLNAME_DATABASETYPE_SERVICE_HOST

The formatting is wrong also in the text below the table.

Second point is: it will be good to unify this formatting in all tables. I mean

vs <PREFIX>.