Speed up builds.

[lina128]

Changes in this PR includes:

1. Remove redundant test conditions in webgl.
2. Layers tests with both firefox and chrome every PR, use chrome should be sufficient.
3. Node and NodeGpu takes too much time to build deps (~9mins), upgrade to a more powerful computation unit.

After test:

• Node and NodeGpu reduced 3 mins.
• Layers and Webgl is mainly saving some browserstack resources.

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This change is 

[tafsiri]

👏 HIGHCPU to the rescue!

Reviewed 4 of 4 files at r1.
Reviewable status: complete! 1 of 1 approvals obtained (waiting on @pyu10055 and @tafsiri)

[tafsiri]

A suggestion, should we also use HIGHCPU on the union package cloudbuild since it builds the converter in its build-deps (and generally has a lot of deps)?

[tafsiri]

Also just for my own understanding which timing are you looking at for the 1-2 min for node/node-gpu? (i tried looking at the logs/build gui for the checks on this PR but didn't see it (or wasn't exactly sure which item you are referring to).

[pyu10055]

Reviewed 4 of 4 files at r1.
Reviewable status: complete! 2 of 1 approvals obtained (waiting on @pyu10055)

[lina128]

I looked at the duration, for this PR it is 6min, for a previous PR it is 9min, also for nightly it is 9min., just changed the description it should be 3 mins improvement! Yeah, HIGHCPU to the rescue! Btw, I found the timing on the left panel less useful, because it includes waiting time.

Will add HIGHCPU to union package in a separate PR. Nice catch!

Reviewable status: complete! 2 of 1 approvals obtained