[Build] ts config for tests (older syntax) for older node.js

[RaananW]

Node 14 and under don't support the 2021 syntax we used when running tests.
From now, when testing we compile to es5

[azure-pipelines]

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[azure-pipelines]

Snapshot stored with reference name:
refs/pull/12972/merge

Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12972/merge/index.html

To test a playground add it to the URL, for example:

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12972/merge/index.html#WGZLGJ#4600

Links to test babylon tools with this snapshot:

https://playground.babylonjs.com/?snapshot=refs/pull/12972/merge
https://sandbox.babylonjs.com/?snapshot=refs/pull/12972/merge
https://gui.babylonjs.com/?snapshot=refs/pull/12972/merge
https://nme.babylonjs.com/?snapshot=refs/pull/12972/merge

To test the snapshot in the playground with a playground ID add it after the snapshot query string:

https://playground.babylonjs.com/?snapshot=refs/pull/12972/merge#BCU1XR#0