ci: change runner dispatch for LuaJIT testing

Before the patch the LuaJIT integration workflow was dispatched to the
runner with the name given via <inputs.host> parameter. Unfortunately,
as a result of runners renaming we can't continue to dispatch the
workflow this way.

As a result of the patch there are two new workflow parameters:
<inputs.arch> to pass the host architecture name (i.e. x86_64 or ARM64)
and <inputs.os> to pass the OS family name (either Linux or macOS).
Considering two values we can choose the proper runner in LuaJIT
integration workflow. Besides, this change bring LuaJIT CI closer to
matrix usage for its integration workflow.

All three workflow parameters are not obligatory for now to avoid
tarantool/luajit CI break on both long-term and working branches. When
all branches are rebased on the new approach, <inputs.host> parameter
will be removed and both <inputs.arch> and <inputs.os> will become
obligatory.

Moreover, the new 'regular' label is also added to <runs-on> list, since
the new "lightweight" runners have been introduced to ghacts-shared-*
pool. There are a couple of LuaJIT tests that requires more memory than
provided by "lightweight" runners, so only "regular" ones need to be
chosen for LuaJIT integration testing.

Last but not least: attentive reader might notice there are strange
values used as a default for <inputs.host> as well as <inputs.arch> and
<inputs.os>. This is ugly hack required for the transition period, since
one can't use empty string or unknown label name within <runs-on> label
list. Hence 'self-hosted' looks like the most robust option for both old
and new behaviours.

NO_DOC=ci
NO_TEST=ci
NO_CHANGELOG=ci

Reviewed-by: Yaroslav Lobankov <y.lobankov@tarantool.org>
Signed-off-by: Igor Munkin <imun@tarantool.org>