Upgrade the GKE cluster used for nightly tests to n1-standard-8

[dmitryduev]

Description

We've started doing more standalone/cloud testing in nightly (yay!!), and the exec times are up as a result:

We've been using a tiny n1-standard-4 cluster yielding 1-2 CPU/pod, which costs us about $20/month. Let's give our tests a bit more CPU/memory, they deserve it :)

Testing

How was this PR tested?

Checklist

• Include reference to internal ticket "Fixes WB-NNNN" (and github issue "Fixes #NNNN" if applicable)

[codecov]

Codecov Report

Merging #4065 (b75158f) into master (6db0993) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4065      +/-   ##
==========================================
+ Coverage   82.75%   82.76%   +0.01%     
==========================================
  Files         255      255              
  Lines       32266    32266              
==========================================
+ Hits        26701    26706       +5     
+ Misses       5565     5560       -5     

Flag	Coverage Δ
functest	54.94% <ø> (+0.04%)	⬆️
unittest	73.48% <ø> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
wandb/sdk/internal/internal_api.py	86.39% <0.00%> (-0.52%)	⬇️
wandb/sdk/wandb_setup.py	88.50% <0.00%> (-0.50%)	⬇️
wandb/sdk/lib/git.py	79.01% <0.00%> (ø)
wandb/cli/cli.py	70.29% <0.00%> (+0.09%)	⬆️
wandb/sdk/interface/interface_shared.py	85.48% <0.00%> (+0.31%)	⬆️
wandb/filesync/step_prepare.py	94.93% <0.00%> (+1.26%)	⬆️
wandb/sdk/lib/sock_client.py	91.36% <0.00%> (+1.43%)	⬆️
wandb/sdk/internal/meta.py	90.79% <0.00%> (+3.06%)	⬆️