Change incorrect exception wording modifying

The word modifying is not correct for this as these queries are not
necessarily "modifying" anything. I think querying is more accurate.

spec/support/database/prevent_cross_joins.rb

@@ -46,7 +46,7 @@ module Database
       if schemas.include?(:gitlab_ci) && schemas.include?(:gitlab_main)
         Thread.current[:has_cross_join_exception] = true
         raise CrossJoinAcrossUnsupportedTablesError,
-          "Unsupported cross-join across '#{tables.join(", ")}' modifying '#{schemas.to_a.join(", ")}' discovered " \
+          "Unsupported cross-join across '#{tables.join(", ")}' querying '#{schemas.to_a.join(", ")}' discovered " \
           "when executing query '#{sql}'. Please refer to https://docs.gitlab.com/ee/development/database/multiple_databases.html#removing-joins-between-ci_-and-non-ci_-tables for details on how to resolve this exception."
       end
     end