IGNITE-13517 Disable travis build until Ignite nightly snapshots packages are published

[Saikat Maitra]

Hi,

I have created a PR to disable travis build from Ignite Extension repo
until Ignite nightly snapshots packages are published. The missing nightly
packages are causing build failure for travis CI since travis is unable to
pull the required Ignite snapshot dependencies.


Jira : https://issues.apache.org/jira/browse/IGNITE-13517
PR : https://github.com/apache/ignite-extensions/pull/24

We also have an open issue to address the nightly packages upload process.

Jira : https://issues.apache.org/jira/browse/IGNITE-13412

Please review and share feedback.

Regards,
Saikat