Fixed set template syntax in block file

[sanganinamrata]

Description

Fixed set template syntax in block file

Fixed Issues (if relevant)

1. Template syntax in block file #15345:Template syntax in block file

Manual testing scenarios

N/A

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

Hi @namratachangani. Thank you for your contribution.
The changes from your Pull Request should be available with the upcoming 2.2.6 release.
Please check the release notes for final confirmation.

Please, consider to port this solution to 2.3 release line.
You may use Porting tool to port commits automatically.