e2e-tests: Align gatling version with gatling-git
e2e-tests: Align gatling version with gatling-git

Align the gatling version used by the framework with the one used in
the gatling-git extension dependency.

This happens to fix the below issue, hence the reporting features.

Bug: Issue 12279
Change-Id: I63a8642ec71caaf2af5bcb12d54b94ff89e21bee

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