This patch adds a temporary workaround for LuaJIT profiling tests to
avoid runners shutdown due to no space left on the disk. The profiling
tests may produce profiles until fully fill up the runner [1].

The workaround is based on implementing disk quotas.

In two words, it creates a 1GB file (disk image), formats this file as
an ext4 filesystem, mounts this filesystem to some mount pont and sets
`LUAJIT_TEST_VARDIR=<mount point>`. In this case LuaJIT tests will use
this dir for storing various test data/profiles and not be able to fill
up the runner.

[1] https://github.com/tarantool/tarantool/issues/7472

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