packer: increase pause_before to 40 seconds

[benipeled]

Following an unknown SSH connection failure raised after the build-machine rebooted

Ref https://github.com/scylladb/scylla-pkg/issues/3646

[benipeled]

Verified by

• https://jenkins.scylladb.com/job/scylla-master/job/releng-testing/job/next-machine-image/207/console
• https://jenkins.scylladb.com/job/scylla-master/job/releng-testing/job/next-machine-image/209/console

2023/11/05 14:39:23 [INFO] (telemetry) ending shell
2023/11/05 14:39:23 [INFO] (telemetry) Starting provisioner file
2023/11/05 14:39:23 ui: �[1;32m==> googlecompute.gce: Pausing 40s before the next provisioner...�[0m
2023/11/05 14:40:03 ui: �[1;32m==> googlecompute.gce: Uploading files/ => /home/ubuntu/�[0m
2023/11/05 14:40:03 packer-builder-googlecompute plugin: [DEBUG] Upload dir 'files/' to '/home/ubuntu/'

2023/11/05 14:40:57 [INFO] (telemetry) Starting provisioner file
2023/11/05 14:40:57 ui: �[1;32m==> azure-arm.azure: Pausing 40s before the next provisioner...�[0m
2023/11/05 14:41:37 ui: �[1;32m==> azure-arm.azure: Uploading files/ => /home/azureuser/�[0m
2023/11/05 14:41:37 packer-builder-azure-arm plugin: [DEBUG] Upload dir 'files/' to '/home/azureuser/'