See #7169 for details about the hide/show prompt feature. In short, it
hides readline's prompt before `print()` or `log.<level>()` calls and
restores the prompt afterwards.

This feature sometimes badly interferes with
`test.interactive_tarantool` heuristics about readline's command
echoing.

This commit disables the feature in `test.interactive_tarantool` by
default and enables it explicitly where needed.

Part of #9985

NO_DOC=testing helper change
NO_CHANGELOG=see NO_DOC

(cherry picked from commit 23094b6f)