[helly25]

Use bashtest 0.7.1's upstream launcher fix and remove XFF's temporary compatibility patch.

AG;DR

• Upgrade mboworks_bashtest from 0.7.0 to the published BCR version 0.7.1.
• Remove the single_version_override, bazelmod/bashtest-launcher-exec-properties.patch, and its Bazel export.
• Upstream Fix launcher execution properties and prepare 0.7.1 bashtest#72 keeps execution properties on the actual test and excludes them from both generated binary launchers. XFF's test.no-sandbox setting remains on full_extras_test.
• No replacement patch, local source override, dependency version workaround, or unrelated cleanup is introduced. The module lockfile is intentionally ignored in this repository.
• Validation: bazel test //xff/cli:full_extras_test //tools:collect_compile_sources_test --config=clang --config=xff_full passed both targets against the published 0.7.1 archive. Normal commit and push hooks passed. This change contains no C++ source edits.
• Generated-rule inspection confirms test.no-sandbox remains on full_extras_test and neither POSIX nor Windows launcher inherits exec_properties.
• Based directly on main after Upgrade five dependencies and fix Bazel integration #1032; independent of the directory-worker performance experiments in Evaluate directory worker admission after the clock fix #991.