test: disable flaky testcases in http_client_test

The testcase "http_client.sock_family:\"AF_UNIX\".test_follow_location"
is flaky in each run of `release_clang_asan` and
`debug_asan_clang` workflows. Disabling a single testcase does not
help. The patch disables a group of testcases executed with Unix
domain socket.

Needed for #9854

NO_CHANGELOG=testing
NO_DOC=testing

(cherry picked from commit 8fae8004f79ecd555537960c60c6e646b037c4cc)