build: make ess version configurable

[kruskall]

The terraform script used for smoke testing was defaulting to the latest version of ess.
Because we want to test on stable versions and allow people to reuse the script to provision and test the dev environment, add a variable to make ess version configurable and default to the latest 8.x version.

[ghost]

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• Start Time: 2022-09-29T23:45:30.994+0000

• Duration: 8 min 22 sec

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Test	Results
Failed	0
Passed	164
Skipped	2
Total	166

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