#36052 ci: Doc: Move all config comments right next to the option they explain

• Place CI config comments directly next to the options they document
• Avoids ShellCheck warnings and improves readability for CI maintainers

This PR refactors CI setup scripts to define BITCOIN_CONFIG using printf rather than multi-line strings. This allows inline comments to sit directly adjacent to the CMake flags they document, avoiding ShellCheck warnings.

Problem: Setting multi-line strings with comments in shell scripts triggers ShellCheck warnings and makes documenting individual flags awkward for CI maintainers.

P4 · cleanup

• P4 because it is a purely cosmetic cleanup for CI setup scripts
• Avoids lint warnings without affecting build correctness or CI reliability

This is an internal cosmetic style refactoring for CI configuration scripts. It changes bash syntax to avoid ShellCheck warnings and place comments inline, having no functional impact on build correctness or CI reliability.

Membership: Changes environment setup scripts across all CI build jobs (ci/test/00_setup_env_*.sh).

Factors: security/stability 0, bug 0, performance 0, user value 0, leverage 0

• Has merge conflicts with the base branch and needs a rebase before review

The PR has merge conflicts with the base branch and is marked as needing a rebase.

Author status: silent since submission

• Uncontroversial cleanup with no objections raised
• Approval ACK without detailed comments (hebasto)

Positive with ACK from hebasto and no objections.

hebasto provided an approval ACK shortly after opening, and no concerns or criticisms have been raised.

• hebasto ACKed commit fa03706fde on 2026-08-22.

Review verdicts (DrahtBot): 1

• ACK: hebasto

Base for: #36042

200 lines under test/bench/ci.

• ci/test/00_setup_env_native_previous_releases.sh +8/-8
• ci/test/00_setup_env_native_asan.sh +7/-7
• ci/test/00_setup_env_native_fuzz_with_msan.sh +6/-7
• ci/test/00_setup_env_native_msan.sh +6/-7
• ci/test/00_setup_env_arm.sh +5/-5
• ci/test/00_setup_env_native_valgrind.sh +4/-5
• ci/test/00_setup_env_native_fuzz.sh +4/-4
• ci/test/00_setup_env_native_tidy.sh +4/-4
• ci/test/00_setup_env_riscv_bare_cross.sh +4/-3
• ci/test/00_setup_env_freebsd_cross.sh +3/-3
• ci/test/00_setup_env_i686_no_ipc.sh +3/-3
• ci/test/00_setup_env_mac_cross.sh +3/-3
• ci/test/00_setup_env_mac_cross_intel.sh +3/-3
• ci/test/00_setup_env_mac_native.sh +3/-3
• ci/test/00_setup_env_mac_native_fuzz.sh +5/-1
• ci/test/00_setup_env_native_alpine_musl.sh +3/-3
• ci/test/00_setup_env_native_chimera_lto.sh +3/-3
• ci/test/00_setup_env_native_fuzz_with_valgrind.sh +3/-3
• ci/test/00_setup_env_native_iwyu.sh +3/-3
• ci/test/00_setup_env_native_nowallet.sh +3/-3
• ci/test/00_setup_env_native_tsan.sh +3/-3
• ci/test/00_setup_env_netbsd_cross.sh +3/-3
• ci/test/00_setup_env_openbsd_cross.sh +3/-3
• ci/test/00_setup_env_s390x.sh +3/-3
• ci/test/00_setup_env_win64.sh +3/-3
• ci/test/00_setup_env_win64_msvcrt.sh +3/-3

PR #36052 refactors CI environment scripts across 26 platforms to construct BITCOIN_CONFIG using printf rather than multi-line strings, allowing comments to sit alongside the flags they document. It resolves minor ShellCheck linting issues and improves readability for CI maintainers. There are no functional or test-runner behavioral changes, making it a low-priority cosmetic cleanup. The PR is currently in a merge conflict and needs a rebase, having received one approval from hebasto.