sw-precache-lab: remove path prefix from imported scripts
sw-precache-lab: remove path prefix from imported scripts

verioussmith/pwa-training-labs,emoreno911/pwa-training-labs,googlecodelabs/workbox-indexeddb,google-developer-training/amp-ilt,googlecodelabs/workbox-lab,googlecodelabs/workbox-indexeddb,googlecodelabs/amp-pwa-workbox,googlecodelabs/amp-pwa-workbox,googlecodelabs/workbox-lab,google-developer-training/pwa-training-labs,google-developer-training/amp-ilt,google-developer-training/pwa-training-labs,verioussmith/pwa-training-labs,emoreno911/pwa-training-labs