Different current working dir for listen socket for different tarantool versions

Create sample app in tt env:

$ cat instances.enabled/app1.lua 
box.cfg{listen='unix/:./aaaaaaa.sock'}

Start it with tarantool 1.10.15 and check where listen socket is created:

$ tt start app1 
   • Starting an instance [app1]...

$ ls -l var/run/app1/
total 4
srwxrwxr-x 1 psergee psergee 0 июн 15 16:06 aaaaaaa.sock
srwxrwxr-x 1 psergee psergee 0 июн 15 16:06 app1.control
-rw-r--r-- 1 psergee psergee 6 июн 15 16:06 app1.pid

Start it with tarantool 2.11 and check where listen socket is created:

$ tt start app1 
   • Starting an instance [app1]...

$ ls -l var/run/app1/
total 4
srwxrwxr-x 1 psergee psergee 0 июн 15 16:12 app1.control
-rw-r--r-- 1 psergee psergee 6 июн 15 16:12 app1.pid

$ ls -l ./aaaaaaa.sock 
srwxrwxr-x 1 psergee psergee 0 июн 15 16:12 ./aaaaaaa.sock

Listen socket is created in current working dir, which is not expected. Suppose, it must be in run dir.

Reproduce the behavior with the sample instances.enabled/app1.lua configuration and compare tt start app1 under Tarantool 1.10.15 and 2.11. Inspect how tt starts the instance and resolves the relative unix socket path. Done means the socket is created in the instance run directory rather than the caller's current working directory, with behavior checked for both versions.