Close #764

It is simpler to reuse the script from other downstream pipelines. They
do not need to know the names of submodules in case they change. With
the patch such a change requires only updates to picodata repository.

It's ignore list for gitleaks

Fix tarantool compilation in CI by disabling bundled libcurl.
Bundled libcurl uses a file we removed because gamayun didnt like it.

This patch changes when we update current_master_name during consistent
master switchover. Now it is updated as soon as we determine that the
new master has synchronized it's vclock with the old master.

As a result we can now block expel of a non-last replica in cases where
other replicas are offline, which is crucial because instances can
easily become offline due to temporary network issues.

Now we assume instance may not respond if
- target state is Offline (non-graceful assumed)
- current state is Expelled

With `git log --format="%an" | sort -u`

It is now possible to write in migration `@_plugin_config.foo` where foo is
variable from plugin configuration. Note that configuration typically
belongs to individual services, in catalog this field is called entity. For
migration special values there is special entity called `migration_context`.
So corresponding alter looks this way:

ALTER PLUGIN p 0.1.0 SET migration_context.foo = '"nondefault"'

(extra quotes are temporary, and should be dealt with separately)

Closes https://git.picodata.io/picodata/picodata/picodata/-/issues/659

Previouslly we've blocked on scope termination before reading from
channel, so blocking still occured.

With this patch there is new `blocking` wrapper function that executes
provided closure on separate thread and yields until result is ready