Use chg in LfMerge, only in local dev LF for now

[rmunn]

Fixes #1841

Description

We'll start using chg for LfMerge in local LF development; once we know that it works, we'll add the relevant environment variable to the k8s deployment so that staging and then prod also start getting the same Send/Receive speedups.

Checklist

• I have labeled my PR with: bug, feature, engineering, security fix or testing
• I have performed a self-review of my own code
• I have reviewed the title & description of this PR which I will use as the squashed PR commit message
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have enabled auto-merge (optional)

Testing

• Run some Send/Receives on local LF and make sure everything still works.

[github-actions]

Unit Test Results

362 tests   362 ✅  13s ⏱️
 37 suites    0 💤
  1 files      0 ❌

Results for commit 223c2fa.

♻️ This comment has been updated with latest results.

[hahn-kev]

looks like our PNPM install is failing in LF too, would you mind looking into that? I'm fine if you merge this PR without fixing it as they're totally unrelated

[rmunn]

looks like our PNPM install is failing in LF too, would you mind looking into that? I'm fine if you merge this PR without fixing it as they're totally unrelated

Huh. So there's some kind of problem with NPM's signing infrastructure and it's unrelated to the specific PNPM 9.15.5 release (LF is still on 9.11.0). Weird; hopefully they sort it out soon because that's going to affect millions of projects.

I'll try rerunning the failed GHA builds once in case it's already been sorted out, then if it's still failing across the board I'll just merge this.

[rmunn]

https://www.github.com/nodejs/corepack/issues/612

[rmunn]

Corepack bug present in the corepack versions distributed with NPM (corepack 0.30.0). Running npm install --global corepack@latest before running corepack enable will update corepack to 0.31.0 which has the bugfix. (PNPM rotated a key, so for a while both the old and new keys were returned from the "send me the key" API endpoint, and IIUC corepack 0.30.0 didn't handle that correctly and only checked against the first key returned, which was the old key.

[rmunn]

That solved the PNPM install issue, only to run into a different issue: "Package libasound2 has no installation candidate" which trying to install browsers for pnpm exec playwright install. I'll work on solving that separately, but I'll go ahead and merge this PR since that error is unrelated to this one and is probably already present on develop.