ci: add debug_asan_clang workflow

Similarly to release_asan_clang but to test debug build. It is also run
only under `asan-ci` and `full-ci` labels.

Fiber stack size is 2 times bigger than in the release workflow for luajit
tests to pass. Note that this factor is a wild guess.

Part of #7327

NO_TEST=ci
NO_CHANGELOG=ci
NO_DOC=ci