Revert "Build: use native target CPU (#1330)" (#1338)

This reverts commit 7b5d5668b3a8949dd56b2a887f10d964d523bdd6.

<!-- The PR description should answer 2 important questions: -->

### What

Deployed different commits to `staging` and this one broke it, so
rolling it back.

V3_GIT_ORIGIN_REV_ID: ba93bbc61b38d2c756e109e24566f8d51b01d458

v3/.cargo/config.toml

@@ -1,6 +1,2 @@
 [net]
 git-fetch-with-cli = true
-
-[build]
-rustflags = ["-C", "target-cpu=native"]
-