ci: upload compact Bazel execution logs for bazel.yml (#16577)

## Why

The main Bazel CI lanes need compact execution logs to investigate cache
misses and unexpected rebuilds, but local users of the shared wrapper
should not pay that log-generation cost by default.

## What Changed

-
[`.github/scripts/run-bazel-ci.sh`](https://github.com/openai/codex/blob/a6ec239a24fd21507bb75a28f17277653f52e3a2/.github/scripts/run-bazel-ci.sh#L149-L153)
now appends `--execution_log_compact_file=...` only when
`CODEX_BAZEL_EXECUTION_LOG_COMPACT_DIR` is set; the caller owns creating
that directory.
-
[`.github/workflows/bazel.yml`](https://github.com/openai/codex/blob/a6ec239a24fd21507bb75a28f17277653f52e3a2/.github/workflows/bazel.yml#L66-L174)
enables that env var only for the main `test` and `clippy` jobs, creates
the temp log directory in each job, and uploads the resulting `*.zst`
files from `runner.temp`.

## Verification

- `bash -n .github/scripts/run-bazel-ci.sh`
- Parsed `.github/workflows/bazel.yml` as YAML.
- Ran a local opt-in wrapper smoke test and confirmed it writes
`execution-log-cquery-local-*.zst` when the caller pre-creates
`CODEX_BAZEL_EXECUTION_LOG_COMPACT_DIR`.