solve the net.git-fetch-with-cli in .cargo/config.toml #5186 problem

[Manojseetaram]

Fixes intermittend SSL error when fetching the iai-calllgrind fit dependcy in ci , caused by cargo's default libgit2-based git client. Shellling out to the system git binary avoids this , Fixes #5186 problem

Description of Changes

API and ABI breaking changes

Expected complexity level and risk

Testing

[CLAassistant]

All committers have signed the CLA.

[Manojseetaram]

Opened #5842 to fix this — the root cause is .cargo/config.toml not setting net.git-fetch-with-cli, so cargo falls back to its default libgit2-based git client, which appears to be what's throwing the SSL error against iai-callgrind's git dependency. Setting that flag makes cargo shell out to the system git binary instead. Validated locally by running cargo ci update-flow --target=aarch64-apple-darwin --github-token-auth, which completed successfully after the fix.

[bfops]

Hi @Manojseetaram, can you help me understand why you think this solves the issue? Why does the built-in client have intermittent SSL issues? The flake is rare, and afaik we've only observed it on our CI machines, where we have seen other suspicious networking-related failures as well.