PMM-14858 Fix external clickhouse scrape

[4nte]

https://jira.percona.com/browse/PMM-14858

[JNKPercona]

Server docker: perconalab/pmm-server-fb:PR-4356-a3c2a26
Client docker: perconalab/pmm-client-fb:PR-4356-a3c2a26
Watchtower docker: perconalab/pmm-watchtower-fb:PR-4356-a3c2a26
Client tarball: https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4356-a3c2a26.tar.gz
Staging instance: https://pmm.cd.percona.com/job/pmm3-aws-staging-start/parambuild/?DOCKER_VERSION=perconalab/pmm-server-fb:PR-4356-a3c2a26&CLIENT_VERSION=https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4356-a3c2a26.tar.gz

[JNKPercona]

API tests have succeded: https://pmm.cd.percona.com/job/pmm3-api-tests/6142/

[JNKPercona]

Server docker: perconalab/pmm-server-fb:PR-4356-0fe333e
Client docker: perconalab/pmm-client-fb:PR-4356-0fe333e
Watchtower docker: perconalab/pmm-watchtower-fb:PR-4356-0fe333e
Client tarball: https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4356-0fe333e.tar.gz
Staging instance: https://pmm.cd.percona.com/job/pmm3-aws-staging-start/parambuild/?DOCKER_VERSION=perconalab/pmm-server-fb:PR-4356-0fe333e&CLIENT_VERSION=https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4356-0fe333e.tar.gz

[JNKPercona]

API tests have succeded: https://pmm.cd.percona.com/job/pmm3-api-tests/6144/