Revert "box: introduce Lua persistent functions"

src/box/alter.cc

src/box/bootstrap.snap

src/box/func.c

src/box/func_def.c

src/box/func_def.h

src/box/lua/call.c

src/box/lua/schema.lua

src/box/lua/upgrade.lua

src/box/schema_def.h

test/box-py/bootstrap.result

test/box-py/bootstrap.test.py

test/box/access_misc.result

test/box/function1.result

test/box/function1.test.lua