ci: fix flag passing

[j2kun]

Previous error was:

Run bazel build -c opt "$BAZEL_CONFIG_FLAG" \
  bazel build -c opt "$BAZEL_CONFIG_FLAG" \
    --remote_header=x-buildbuddy-api-key="$BUILDBUDDY_API_KEY" \
    //...
  shell: /usr/bin/bash -e {0}
  env:
    BUILDBUDDY_API_KEY: ***
    BAZEL_CONFIG_FLAG: --config=ci --config=remote
2026/06/23 18:21:30 Downloading https://releases.bazel.build/8.4.0/release/bazel-8.4.0-linux-x86_64...
Starting local Bazel server (8.4.0) and connecting to it...
ERROR: Config value 'ci --config=remote' is not defined in any .rc file
INFO: Invocation ID: af845015-d465-48d7-b824-bfd96830719f
INFO: Streaming build results to: https://heir.buildbuddy.io/invocation/af845015-d465-48d7-b824-bfd96830719f
Error: Process completed with exit code 2.

So the quoting of the env var was making bazel treat ci --config=remote as a single config name. Use a workaround to still quote but also allow multiple args.