webpack: Tighten jshint path match
webpack: Tighten jshint path match

The pattern apparently applies to a full absolute path, not a relative
one within the source tree. Thus it would previously also catch
checkouts which had a `/src` parent directory anywhere.

Tighten the path match to avoid that.

Closes #10686
martinpitt/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,andreasn/cockpit,cockpit-project/cockpit,andreasn/cockpit,mvollmer/cockpit,martinpitt/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,andreasn/cockpit,moraleslazaro/cockpit,garrett/cockpit,deryni/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,andreasn/cockpit,garrett/cockpit,cockpituous/cockpit,garrett/cockpit,andreasn/cockpit,deryni/cockpit,andreasn/cockpit,deryni/cockpit,cockpituous/cockpit,andreasn/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,deryni/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,martinpitt/cockpit,deryni/cockpit,cockpit-project/cockpit,garrett/cockpit,cockpit-project/cockpit,mvollmer/cockpit,garrett/cockpit,mvollmer/cockpit,cockpituous/cockpit,deryni/cockpit,moraleslazaro/cockpit