Revert "ci(lint): skip remote config schema verification"

This reverts commit d7d8dd25.

The lint job failed on a transient timeout fetching the golangci-lint
config schema, which is a CI infrastructure concern rather than a defect
in this change. Disabling schema verification to work around it does not
belong in a cache-hardening PR: it weakens a check for every future run,
and its root cause is out of scope here. Leaving CI configuration
untouched keeps this PR to the lockdown cache redesign.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>