Add default server restart to each test run

[avtikhon]

Patchset of 3 patches:

1. Found that the root cause of the issues happened with vinyl tests were
   backside effects of the not correct test 'vinyl/gh.test.lua' which
   leaved Tarantool worker process in inconsistent state. After it any
   other next test on the same Tarantool worker process could fail on
   running testings with snapshots calls, like test: flaky vinyl/bloom.test.lua fail because of previous vinyl/gh.test.lua on Snapshot is already in progress tarantool-qa#126:

     error: Snapshot is already in progress
   

   Either restarting Tarantool worker process could fail on stopping it,
   like ./test-run --gdb is broken in 1.6 tarantool#261 and test: flaky vinyl/gh.test.lua test tarantool-qa#205:

    E> failed to process vylog record: delete_slice{slice_id=115, }
    E> ER_INVALID_VYLOG_FILE: Invalid VYLOG file: Slice 115 deleted but not registered
   

   Decided to avoid of such situations for now and in the future all tests
   must be run after Tarantool worker default server process was restarted.
   This patch moves this server restart call from check if the test failed
   to the common part of the tests run loop.

   Part of resources: disk bound tests need to run in special way tarantool-qa#97
   Fixes Problems with installing tarantool-modules on master tarantool#260
   Fixes ./test-run --gdb is broken in 1.6 tarantool#261
   Needed for test: flaky vinyl/deferred_delete.test.lua tarantool#5089
   Closes test: flaky vinyl/bloom.test.lua fail because of previous vinyl/gh.test.lua on Snapshot is already in progress tarantool-qa#126

2. After the previous commit in the current patchset we don't use the same
   tarantool server process from test to test and we don't need to use any
   scripts like 'pretest_clean.lua' to cleanup it between tests. So this
   patch removes this script.

3. Found that all currently used suite.ini files use this option enabled.
   Also there is no need to have any suite of tests where snap either
   log files whould be used by the next test from the previous, due to
   such test schema can be easily implemented within single test file.

[Totktonada]

Needed for tarantool/tarantol#5089

Typo: tarantol -> tarantool.

[Totktonada]

Please, look at the comment in TarantoolServer.pretest_clean(). It becomes non-actual.

In fact, xlog/snap are removed between tests, but in very non-obvious way (and it does not depend on the pretest_clean suite.ini option anyhow). Please, at least update the comment. Maybe it also worth to drop the option at all and always perform clean up between tests.

Actually the following code removes xlog/snap:

test-run/lib/tarantool_server.py

Lines 715 to 717 in fd3e5f2

	color_log(' | Found old workdir, deleting...\n')
	self.kill_old_server()
	self.cleanup()

I propose to spin around the code for a hour and decide about some 'good enough' amount of changes we'll do now (postpone everything else a bit).

[avtikhon]

Please, look at the comment in TarantoolServer.pretest_clean(). It becomes non-actual.

In fact, xlog/snap are removed between tests, but in very non-obvious way (and it does not depend on the pretest_clean suite.ini option anyhow). Please, at least update the comment. Maybe it also worth to drop the option at all and always perform clean up between tests.

Actually the following code removes xlog/snap:

test-run/lib/tarantool_server.py

Lines 715 to 717 in fd3e5f2

	color_log(' | Found old workdir, deleting...\n')
	self.kill_old_server()
	self.cleanup()

I propose to spin around the code for a hour and decide about some 'good enough' amount of changes we'll do now (postpone everything else a bit).

I've tried with and w/o clean and saw that this function is still needed. Also checked that it calls on tests starts with 'core = tarantool' suite. Found that there is no any test suites suite.ini file that use this option. Also there is no need to have any suite of tests where snap either log files whould be used by the next test from the previous, due to such test schema can be easily implemented within single test file. It means that this option 'pretest_clean' is a dead code and not needed at all. So I've added tiny patch to remove it.

[Totktonada]

To be honest, I'm not very happy about the code: it is more complex then it would be. However, it seems, everything works as expected, so it looks as a way to go.

[Totktonada]

Updated the test-run submodule in tarantool in 2.9.0-104-g7fa70b661, 2.8.1-75-g029d66355, 2.7.2-62-g6f9ccad83, 1.10.10-25-g9b4acec8f.