Fixes recent scripting breeze fix to work also with zsh (apache#14787)

The BASH variable introduced in apache#14579 is not set when the main shell is
zsh on MacOS (which is the default) this PR changes it so that the
output of `command -v bash` is used instead.

Fixes apache#14754

(cherry picked from commit c613384)

Author: potiuk

breeze

@@ -25,7 +25,7 @@ if [[ ${BREEZE_REDIRECT=} == "" ]]; then
     mkdir -p "${AIRFLOW_SOURCES}"/logs
     export BREEZE_REDIRECT="true"
     if [[ "$(uname)" == "Darwin" ]]; then
-      exec script -q "${AIRFLOW_SOURCES}"/logs/breeze.out "$BASH" -c "$(printf "%q " "${0}" "${@}")"
+      exec script -q "${AIRFLOW_SOURCES}"/logs/breeze.out "$(command -v bash)" -c "$(printf "%q " "${0}" "${@}")"
     else
       exec script --return --quiet "${AIRFLOW_SOURCES}"/logs/breeze.out -c "$(printf "%q " "${0}" "${@}")"
     fi