fix: attempt to fix ci build failures.

[jeeyyy]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message(s) follow our guidelines: https://github.com/dequelabs/axe-core/blob/develop/doc/code-submission-guidelines.md#git-commits
• Changes to rules and checks appropriately support Shadow DOM
• Changes have been tested in major browsers and Assistive Technologies
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Description of the changes

• Tackled the issue of CircleCI kicking the bucket intermittently due to timeout error on script execution for mobile web-driver (chrome-mobile).
• Github issue: Fix flakiness of integration tests on Circle CI #805
• Although this looked like grunt concurrency, or non-availability of gecko-driver, or docker base image issue, this was purely a configuration for web-driver.
• Also over-rid node ENV to not default to Http2, to avoid experimental warning on the terminal.

Does this PR introduce a breaking change?

• Yes
• No

Other information

• Refer Circle CI for relevant commit to see logs (https://circleci.com/gh/dequelabs/axe-core/1164)

[WilcoFiers]

Lets run this a bunch of time to see if it solved the problem.

[jeeyyy]

re-ran build multiple times, succeeds on each run - https://circleci.com/gh/dequelabs/axe-core/tree/build-failure-fix

[dylanb]

@JKODU you have mixed style changes into some fix commits, this goes against our commit guidelines. Can you undo the style changes and put them into a separate commit.

[jeeyyy]

@dylanb sure thing.

[dylanb]

@JKODU looks like this got merged already

[jeeyyy]

@dylanb
Yup, we merge before this was raised, to help with reducing the number of re-builds we had to run. Will cater to the requested changes in the next issue I am tackling. In my radar.