[all_tests][ci] Use .zshenv to avoid conda setting up breaks the pipe…

…line (#30999)

We have seen mac wheel build failures like when setting up the environment. 

The error was raised when doing `source ~/.zshrc` which contains 
- an export PATH to include bazel that `ci.sh init` puts in
- default conda activation code comes with the sandbox. 

We don't use condas for the mac builds and tests I believe, and this PR moves the PATH export to `.zshenv` for environment.

(This also reverts the PR: #30911) 

Signed-off-by: rickyyx <[email protected]>

.buildkite/pipeline.macos.yml

@@ -14,7 +14,7 @@ prelude_commands: &prelude_commands |-
  rm -rf /tmp/bazel_event_logs
  cleanup() { if [ "${BUILDKITE_PULL_REQUEST}" = "false" ]; then ./ci/build/upload_build_info.sh; fi }; trap cleanup EXIT
  (which bazel && bazel clean) || true;
- . ./ci/ci.sh init && source ~/.zshrc
+ . ./ci/ci.sh init && source ~/.zshenv
  ./ci/ci.sh build
  ./ci/env/install-dependencies.sh
  ./ci/env/env_info.sh
@@ -46,8 +46,7 @@ steps:
  - export MAC_WHEELS=1
  - export MAC_JARS=1
  - export RAY_INSTALL_JAVA=1
- - . ./ci/ci.sh init 
- - source ~/.zshrc
+ - . ./ci/ci.sh init && source ~/.zshenv
  - ./ci/ci.sh build
  # Test wheels
  - ./ci/ci.sh test_wheels

ci/env/install-bazel.sh

@@ -59,9 +59,9 @@ if [ "${BAZEL_CONFIG_ONLY-}" != "1" ]; then
  "${target}" --user
  # Add bazel to the path.
  # shellcheck disable=SC2016
- printf '\nexport PATH="$HOME/bin:$PATH"\n' >> ~/.zshrc
+ printf '\nexport PATH="$HOME/bin:$PATH"\n' >> ~/.zshenv
  # shellcheck disable=SC1090
- source ~/.zshrc
+ source ~/.zshenv
  elif [ "${CI-}" = true ] || [ "${arg1-}" = "--system" ]; then
  "$(command -v sudo || echo command)" "${target}" > /dev/null # system-wide install for CI
  else