Reduce the number of connections to the database from CGImap

[Rub21]

Having 30 instances connected to the DB for cgimap is generating issues

[Worker(host:production-osm-seed-web-5c9c5db786-zbw9g pid:275)] Starting job worker
[Worker(host:production-osm-seed-web-5c9c5db786-zbw9g pid:275)] Error while reserving job: connection to server at "172.20.67.93", port 5432 failed: FATAL:  sorry, too many clients already
[Worker(host:production-osm-seed-web-5c9c5db786-zbw9g pid:275)] Error while reserving job: connection to server at "172.20.67.93", port 5432 failed: FATAL:  sorry, too many clients already
[Worker(host:production-osm-seed-web-5c9c5db786-zbw9g pid:275)] Error while reserving job: connection to server at "172.20.67.93", port 5432 failed: FATAL:  sorry, too many clients already
[Worker(host:production-osm-seed-web-5c9c5db786-zbw9g pid:275)] Error while reserving job: connection to server at "172.20.67.93", port 5432 failed: FATAL:  sorry, too many clients already
[Worker(host:production-osm-seed-web-5c9c5db786-zbw9g pid:275)] Error while reserving job: connection to server at "172.20.67.93", port 5432 failed: FATAL:  sorry, too many clients already
[Worker(host:production-osm-seed-web-5c9c5db786-zbw9g pid:2

I am reducing the number of connection to DB to 10 .

cc. @batpad @1ec5 @danrademacher @mmd-osm