After adding the autorequiring luatest [1,2], there is no need to use
the following approach now:

```
local t = require('luatest')
local g = t.group()

server:exec(function()
    local t = require('luatest') -- duplicate
    t.assert(...)
end)
```

Modern approach looks like:

```
local t = require('luatest')
local g = t.group()

-- `t` already available in the remote server
server:exec(function() t.assert(...) end)

-- also it works with any variable
local my_custom_t = require('luatest')

server:exec(function()
    my_custom_t.assert(...) -- already available
end)
```

[1] tarantool/luatest#277
[2] tarantool/luatest#289

Part of tarantool/luatest#233

NO_DOC=test fix
NO_TEST=test fix
NO_CHANGELOG=test fix

Changed the work with hooks in the part of tests.

Legacy approach:

```
g.before_all = function() ... end
g.after_all = function() ... end
```

The logic of executing hooks will be expected and
more controlled if use following approach:

```
g.before_all(function() ... end)
g.after_all(function() ... end)
```

Resolve #8066

NO_DOC=test fix
NO_TEST=test fix
NO_CHANGELOG=test fix

Some internal modules have been recently copied to luatest repo [1,2]
and now they can be safely removed, and the corresponding functionality
from luatest can be used instead.

Affected modules:

- test/luatest_helpers/server.lua

[1] tarantool/luatest#258
[2] tarantool/luatest#266

Closes tarantool/luatest#239

NO_DOC=testing stuff
NO_TEST=testing stuff
NO_CHANGELOG=testing stuff

Reuse check_param_table() funciton in box begin instead of some custom
parameter checking code.
As one of the side effects, unknown options are now declined by
`box.begin{}`, which becomes more and more important with new options
introduction.

In-scope-of #6707

NO_DOC=refactoring
NO_CHANGELOG=refactoring